wow, that's a very broad question.
first off, think in terms of the admin and DJ being a user level. you need to implement user level authentication. see the "User Level Authentication" tutorial in the archived documentation section of the security assist support page:
once you have user level authentication in place, you can create the admin pages and restrict access to them based on the user level session variable.
for the dj pages, when a user logs in, their user id is stored in a session variable. if you look at the way the user update page is configured, the recordset is set to filter the user id column on the iuser ID session, it is this userID session that allows you to relate information to a specific user.
for the profile photo, you will need to use the file manipulation portion of Universal Email or CSS form builder, add a photo column to the users table to hold the file name.
see the "How to apply Digital File Pro to DataAssist Insert and Update pages" tutorial on the data assist page for details on configuring the update server behavior:
you will also need to add columns for top 10 tunes etc to the users table and add form elements for these to the userupdate page.