Your not going to get an answer to this, there is no magic wand you can use to change what your asking without working it out yourself, or at the very least supplying some actual code with your question.
To change the CSS in a back-end option page you can use the Options API, http://codex.wordpress.org/Options_API, or write a custom CSS file and include it in your header.
As Mark already mentioned there is a color picker that comes with WordPress that you can use to fill in your custom field options with color values.
Related Posts:
- Alignment Problem [closed]
- What is an alternative to not using child theme to customize a WordPress theme?
- How to customize the colors within a stylesheet using a WordPress setting
- how can I re-utilize and class on a child theme
- Theme.json: creating different sections of the color palette
- how can I add an icon/image for a child theme?
- WordPress API Menu/Submenu Order
- WooCommerce shop page to use my custom template [closed]
- What are the advantages and disadvantages of Option Tree over the Customization API?
- How do I add settings to the Background Options Page?
- My child theme doesn’t work Error: “The parent theme is missing. Please install your parent theme”
- How To Add New Option Types To Option Tree?
- Is it possible ( or advisable) to allow open access to the new theme customizer for potential clients?
- Child Theme vs Duplicate Theme Renamed
- What WP folder can I use to write files to?
- WordPress Settings API error
- Add a dropdown to theme customizer
- Understanding wp_add_inline_style
- Add a new checkbox in theme options
- Hide a div that is part of all pages on one specific page
- How to: Update live sites theme from version control repo via plugin or library? [closed]
- Setting multiple default background images?
- Best practice way to implement custom sections into a WordPress theme
- Adding Action Hooks In Parent Theme For Easier Child Theme Customization
- Best practice (forward compatibility) for theme options
- How to edit bbPress template files – WordPress + BuddyPress + bbPress? [closed]
- Best practices – Should I create a child theme vs. customizing a framework theme? (such as HTML5 reset)
- Add colors to existing color palette without replacing it
- Child Theme not loading parent CSS
- How to set the default value of a option in a theme?
- add generated stylesheet from parent theme after child-themes style.css
- Where is default wp_head() implemented?
- Add a preview to a WordPress Control Panel
- add_image_size is scaling, even though crop is set to true
- WordPress settings API error when checkbox unchecked
- How to deploy a new theme/theme options from staging to production site
- WordPress Customizer Typography: How to load just the unique Google Fonts?
- use add_action(‘wp_head’) in a widget for generating dynamic CSS styles
- Change Genesis Tag from Page Template [closed]
- How do I get my child-theme to work with my theme’s includes folder?
- What is the best way to export and import theme options?
- How do I get a parent theme modification from a child theme?
- esc_url not working within add_settings_field callback
- WP Gutenberg custom block – generate theme colors from SASS and use them in the inspector and php callback
- CSS in child theme not overriding the parent theme [closed]
- How to remove menus section from WordPress theme customizer
- Modifying JS files in Child-theme
- WordPress Errors in generated by theme check plugin [closed]
- WordPress Theme customisation CSS
- Optimal solution to develop a wordpress theme?
- Adding WordPress colorpicker in widget settings
- When developing a distributable Theme, does it HAVE to be “inheritable”?
- Nesting Functions within Functions
- Should I update my _s theme?
- Create a theme by combining a parent and a child theme
- How to keep my custom theme changes after updating genesis child theme
- Select front page and blog page in custom theme settings page
- De-registering parent style sheet css recommended?
- Where is the correct place(s) in twentysixteen’s header.php to add a Google webfont?
- Can I customize any WordPress parent block-based theme template files by child theme like a parent classic theme?
- WordPress Multisite: Have the same header and footer of main-blog on all sub-blogs
- Modify Javascript Configuration Options for Theme Customizer Colour Picker
- Can a child theme based on Starker theme be released as free to use theme for public use?
- Using the theme options to change background
- Cannot update WordPress General Settings Site Title and Tagline
- Theme Options page not showing up in admin menu
- Override Constants in Child theme
- Changing order title and featured image in blog post (Astra theme)
- Loading files for theme and child theme (Require)
- How to hook CSS file according to theme selection in the customizer section
- How Can I Create a List of Values to Be Iterated Through via WordPress Customization API?
- Change setting name in Customizer and keep the data
- Cutomize Colors utility: How to add more configurable colors to a theme
- Is there a way to activate different theme for specified users? [closed]
- how can I remove the sidebar from my wp homepage [closed]
- Unhook action from child theme
- Does any theme support child theme?
- Am I supposed to create a child theme for every theme I use?
- after_setup_theme, Global Variable and Theme Customizer
- Child themes: disabling the parent
- How to Edit the style of header title of Twenty Eleven Theme?
- How to remove a file included in parent theme with locate_template() via child theme?
- Can’t override template file in child theme
- Is there an action for save_menu and/or update_menu?
- Child theme style.css versioning
- Cannot figure out how to overwrite files in child theme
- How to add theme support?
- Removing non native customizer settings from a child theme
- For best DB performance should I serialize all theme options together or by type?
- Set multiple templates per post
- Creating Theme Options Page
- Location of theme options page menu icon
- WordPress add options to theme not displaying
- qTranslate with my own theme and settings
- Link to a .po file in a child theme
- Alias to theme folder for local development
- Create wordpress header with custom logo in between the menu splitting the menu into two equal parts [closed]
- Inheritance of parent theme plugin files in a child theme
- Divi Child Theme not appearing in “Themes” [closed]
- Access theme options in templates