Steam Problem and Rp_downtown_v2 problem

When i was checking my files for steam so i could add rp downtown it wasnt there!Steam isnt in Add/Remove program its not in my computer but i can still play games on steam.and that happened after i but a rp downtown v2 in my maps rp downtown problem:when i put it in maps when i play a rp server with downtown it says missing maps.please help