You can create an account through the account_overview page, which is accessible to the administrator.
In this training, you will find all the information on how to create and manage roles.
Mendix Academy - 9.4 Access Rules
The home page for a specific role can be set in "Navigation" on the role-based home page.
If a certain role hasn't been granted access to a page, they won't see it in their application. You can add pages to the navigation menu.
I recommend familiarizing yourself with
Mendix Academy - Crash Course and Mendix Academy - Become a Rapid Developer
They provide fundamental knowledge that you will be able to use to develop your applications faster.
Best regards,
Adam