With homepage, you mean the initial landing page? So Login page?
If yes, there is a seperate .html file in your theme folder which you would need to adjust.
If you don’t know HTML, I would recommend making a custom Login page within Mendix so it’s easier to maintain for future development.
If it’s not the login page, you should be able to apply this in the layout you’re using for your homepage.
I didn't knew that there was a seperate .html file. This was just where i was searching for! :D