A positive skin test indicates past exposure. It can occur with no evident disease, or with active disease; BCG vaccine is used in some other countries and can also cause a "false" positive for several years after vaccination. By itself, a positive skin test is not a panic situation.
Depending on your age, chest x-ray, and the context in which it was ordered it can be observed only, treated with months of antibiotics to root out any hidden infection thus preventing active disease in the future, or receive full blown treatment. Preventive antibiotics are a tradeoff decision, since the older you get the more likely the common drugs are to cause liver inflammation.
Hope that helps.