No offense, but you can't just up and learn a new language on a whim...it takes months, years. A lot of studing, a lot of money, and a lot of will power.
Well it depends how strong your whim is. It does take a while but it's quite possible.
I've learned English that way and I'm teaching it now. I think BXPCQ (sorry can't remember the exact name) also learned Japanese and English that way.