Why aren’t my posts/pages showing up in my WordPress Theme?

Try this basic template layout

<?php
    get_header();                           # gets header.php contents

    if (have_posts()):                      # checks if there are any post available for this url
        while(have_posts()):                # starts loop
            the_post();                     # assigns $posts global

            the_title();                    # outputs post title
            the_content();                  # outputs post content
        endwhile;                           # ends loop
    endif;                                  # ends conditional check

    get_footer();                           # gets footer.php contents