From the home screen, click the “Setup” option.
Wtihin the setup menu, type in “profiles” in the search bar on the left, and the click on profiles under Manage Users
From the Profiles menu, select the specific profile you would like to enable visual pages for. If you would like to enable multiple profiles, you must select the profiles one at a time.
After you select the specific profile and are on the custom profile page, you must scroll almost all of the way down until you get to the Enable Visualforce Page Access heading. Click the “edit” button.
You can then select which visualforce pages you would like to enable for this profile. Press “save” when you are done select pages.