In order to assign a user to an entry you have to:
Go to the entry page:
1. Find the Entry you want to assign a User to.
2. Click on the blue button underneath the name of the Entry called "Actions".
3. Click on the second item from bottom that reads "User access..."
4. Then click on "+ Add" and start typing the name of the User.
5. The console will ask you if this is the correct User you want to choose. If so click on "Ok".
You only be able to see Users that have registered on your tribalogic website.