Vacuum line has come unplugged

What is your question?

One of the vacuum lines has come unplugged. Still attached to the vacuum ball (reservoir?). Its the one on top (I know that doesnt help without a picture). I have no idea what it goes to. Any help? I don't know a ton about cars, but I can fix stuff it's explained to me. If I have to move any parts in the engine I won't be able to do it. Do I need to go to a mechanic?

How long has your 2001 Ford Ranger had this problem?

About a week