NWR - need help with recommendation letter

Hi, I am a regular poster here.
A former coworker has asked me to write her a recommendation letter. She is a friend of mine, but I didn't really work on any projects WITH her. She was let go by the firm. Now, the questions are..
What kind of letterhead do I use? Obviously, not my company letterhead.
We are at the same level, can I write her a recommendation letter? I always thought recommendation letters come from someone above you.

TIA

what do I put on the letterhead. Do I put my name and my home address with the phone number? HELP!!

Is she asking you for a recommendation as a friend/co worker? If so then you dont necessarily need letterhead.

You can just sign off on the bottom

Mrs. Smith
124 John Street
Wherever, NY 39775
(123)456-7880

Or you can center this on top of the letterhead if you want to.

HTH