Silly question

I just wondered the same thing myself when I just joined a week ago:)
Found this, depending on how you are logged in:
http://myfitnesspal.desk.com/customer/en/portal/articles/12032-how-do-i-invite-a-current-member-to-be-my-friend-on-myfitnesspal-

Hope that helps ya

For me ( I know each platform is a lil different) I can click on their avatar and it brings me to a screen where I can choice to send a message , add as friend or ignore ( or something like that )
So maybe try clicking on their pictures and seeing if it brings you to the persons page. I'm not great at this so this is the best answer I have but hopefully you will get some other replies