Generally speaking a bride will wear her engagement ring and wedding band on her left hand fourth finger commonly known as her 'ring finger', but when it comes to garters there is no rule.
There is no traditional leg that a garter should be worn on. Garters were designed to keep stockings up on both legs, and so it can be worn on any leg that feels natural to you.
We recommend you wear your garter just above your knee on either leg. This is the most comfortable place to wear it as this part of your leg is least likely to rub against your other leg. Remember, you generally wear this garter all day, so comfort is key!