Call the number to your recruiter, once you've called them, just say, "Hi! I am interested in joining in United States Air Force and I wanted to make an appointment." They will answer few questions. For example: Your name, last, age, do you smoke, what school did you graduate, any medical problems, etc.
*Remember, sometimes they will not pick up the phone because they're out of town, out of office, etc. If you cannnot get in touch with them for weeks, I suggest you go to the recruiters office or try calling in a different city, there all many more recruiters out there!
Next, they will set a appointment for you to come. Once your appointment date arrives, you will drive over to your recruiter's office and they will either let you take a mini ASVAB test or ask you simple questions and then let you take the mini ASVAB test. They will assist you to a room where you can take it. Some recruiters office will let you take it on the computer (which is timed), other recruiter office will let you take it on a paper(which will not be timed.) You will have to get at least a 31 or 50. (I cannot remember all the questions on the mini ASVAB test, but I will post all the questions that I do remember sometime soon.) And maybe you'll get a passing score? ^^* You CANNOT get below 31, if you do..they will not talk to you!