The recruit screen is where you can sign new fighters and coaches to your gym.
Clicking on a fighter or coach will allow you to make an offer, which if it is fair enough they will accept. How much you can offer is determined by the following formula: (income from classes + total cash / 12)
Fighters with more wins will want more cash than unproven ones.
Similarly, with coaches the ones with more expertise will be more expensive.
You will receive a message in your mail a day or two later with their response.