Where on earth is the Squadron menu in Barracks?

I have 3 recruits and for the life of me I have NO idea were to go to send them on missions. I'm baffled.

I think you have to do challenge logs until you attract a new recruit under your timer section, after you speak to the guy in charge in the barracks.

You need 4 befor it shows up

Yes, you need to do challenge log entries to get new recruits. How many is RNG based. It took me 7 challenges to get my first recruit. But only 2 more to get another.
Friends of mine got a recruit after the first completed challenge.

Yup, basically what they said. You need 4 or more recruits before you can start sending them on missions or for advanced training. You get more recruits randomly by completing entries in the challenge log(i got one for doing roulettes, and a 2nd for gathering 100 items - none for the other 8 challenges ive completed so far). The menu for missions will be from talking to the guy(was he a sergeant?) in the barracks room. The enlistment menu is a stack of papers on the table. And the training menu will be one of the bulletin boards.

Once you have 4 members, the sergeant will explain the next bits, having you send them on a short mission and then training. After that, you get to choose what to have them do:

Talk to the sergeant to deploy squad members on missions, or to get instructions on how missions and training work.

The bulletin board is for assigning training, or for checking the squad roster.

Enlistment papers on the desk let you accept new members when they apply.