Patricia, it looks to me like some profiles you manage already have sources, so you should be able to duplicate the process you've used for them.
In general, there are two methods of adding sources--in-line citations, or simply listing all the sources in the Sources section.
For the latter, just go into edit mode, find the Sources heading, type an asterisk (for each source; this will create a bullet point), and then describe each source.
If you want to try in-line sourcing, then following the fact that you have a source for, type "<ref>", then describe the source, then type "</ref>". That will create an in-line source.
You can always view your edits with the Preview option before committing to them.
For more complicated sourcing, you can go into edit mode and view what others have done on various profiles.