Whatever you want. I really recommend answering the
common twenty questions for your character. By the end of that, you'll have everything you need to build your character.
For stealth and weapons, depending on weapons, you can be anything from an ex-SWAT member, to a gang member with an aptitude for blades, to a disgruntled clown that likes to sneak into peoples closets and burst out with a shotgun. Shadowrun is really a game where you come up with whatever concept you want, and roll it into the skills. I've seen everything from drag queen ghoul adepts to two bit drug dealers named Jay and Bob that decided to play face/enforcer.