Questions about masturbation, girls preferred please...?

Yeah, well, I'm 12 (well in one month I am) and I just began masturbating. The first time I got about 5 orgasms, and it was great. But guilt overtook me and I stopped. Now I'm trying again and would like tipss... like perhaps you could tell me if this is a normal thing or not. ...I have no idea what genitals and those things are.. I do it to release stress. I heard someone say while I was in the washroom they use vegetable oil???