A "jock itch" is usually referred to as a type of fungal infection in the groin area. It is in the same array of skin conditions (called "tinea") as athlete's foot and ringworm, which are all caused by various types of fungi. Good hygiene is key to preventing these fungal infections, however in athletes, they sometimes can't be avoided due to long periods of exercise and sweat which create favorable conditions in skin folds for these fungi to proliferate.
Jock itch and athlete's foot are relatively common and fortunately, they are relatively easy to treat. In most simple cases of "tinea cruris" (more commonly known as "jock itch"). Topical antifungal creams applied daily for 2-4 weeks can usually treat the problem. Ketoconazole is one example of antifungal cream that can help treat jock itch.
Most cases will resolve with the topical creams. If they don't you may need a prescription strength topical cream or rarely, in a severe refractory case, you may need antifungal pills such as Griseofulvin for 2 weeks.
As always, to be sure that your self diagnosis of jock itch is correct, you should consult a primary care physician
to make certain that your symptoms are not caused by another condition.