The term "homepage" usually means the site that appears when you first open your web browser. Typically, it has nothing to do with email (although one can set a homepage to an email site if desired).
The easiest way to "find" your homepage is to exit from your browser and then start it up again. The page that appears when you start is your homepage.
In some browsers (e.g., Internet Explorer and Firefox), you can click on a house-shaped icon on the browser's toolbar to go to the home page:
IE:
Firefox:
In IE, you can set the homepage by clicking the "gear" icon (see above) and then clicking "Internet Options."
If Firefox, you can set the homepage by clicking the 3 horizontal bars in the upper right corner, then click "Options," and then click "Home"
In Chrome, click the 3 vertical dots, then "Settings." The homepage setting is under "On startup"