No No No No !!!!!! With ignorance on this level, please stay the hell away from steroids. You might give yourself a huge clitoris, permanent changes to your facial structure so that you look like a man in drag, a deep voice, adams apple.
Steroids are used by women who have reached their maximum muscle gain, and wish to have a physique that is very different from the popular feminine form. Also, going this route is a 24/7 job. Diet and training are the foundation, and without these, you'd most likely get the aromatisation effects mentioned above, without any muscle gain. Getting muscle is one thing - keeping it is another.
Ephedrine is good for weight loss, as is Phentermine. Or start exercising hard. Steroids are not a trouble free instant fix !