I'm assuming the supplement you are referring to is a "nitric oxide" booster. These supplements don't do anything to make you bigger and stronger. Anyone who tells you otherwise has not looked at the actual research.
The best supplement is creatine monohydrate. Protein powders are a convenient way to get extra protein but aren't completely necessary. Add a multivitamin and fish oil and you are set--you don't need anything else.
I always encourage beginners to invest in a program like Ferruggia's
Muscle Gaining Secrets (yes, the name is corny, but it's a good program).