How do i go about tacking my girl with me when i join the military?

This is my situation. Im 21 years old and i been dating the same girl for 5 years now, we have a 1 moth old beautiful daughter together and we have talked about getting married. Im about to join the Army! I want to do Infantry. HOOOAH!! I have my Physical on Wednesday.How do i go about tacking my girl with me when i join the military? What is the best way to go about this? Should i get married before or after i come back from BCT? Whats the process for this? Does my contract have to specifically state that my girl is coming with me? Thanks!