You say a curve, so how bad is this curve then,?this can also depend or which way you hang you penis in your pants, try getting some close fitting jocks and hang it to the left, this will take some time, its not an instant thing.
Most men curve the way we hang our penis's in our pants and to be honest most hang to the to the left so most of us have a small left curve. or dont worry about if your can still shoot your load when you masterbate, then you will get a girl pregnent.
Many men have a slight curvature or bend towards one side or the other, up or down, or a combination of these, and that is normal. Sometimes there can be medical reasons why a bend may be there, which is not normal...however common things being common more than likely your "bend" is normal. If it causes you pain, sexual dysfunction, or concern go get examined by your doctor.
One medical condition to be aware of that can cause a bend in the penis during erection is Peyronie's Disease, which is basically a scarring of the underlying structure of the penis.