I am not sure what you were expecting but you seem to misunderstand what WordPress is, how it works, and what it is for.
WordPress is a web application. If you want to use it you have to run it on a web server. If you want people other than yourself to see the site you have to run it on a public web server like that provided by Dreamhost. This isn’t a matter of Dreamhost creating “problems”. This is just how it works.
You have installed WordPress on a web server operated by Dreamhost. The files will be on that server, which is in a data center somewhere and not on your mac. To access those files you will need software such as FileZilla or whatever web based access Dreamhost might provide.
If you are going to be developing or a theme or child theme, or creating a plugin, I recommend installing a “development” copy on your computer. You don’t want to be hacking on a live site. And strongly advise against ever using the file editor built into WordPress for anything but small CSS changes. That editor is like working on airplane while it is in the air– very dangerous.
You may want to look into desktop clients to make working with WordPress a bit more familiar.