Kegels?? What am I doing wrong!?

Okay ladies so I am 24 weeks pregnant with my second baby and I have noticed my bladder taking a huge hit. I cannot sneeze without my bladder completely emptying itself. I have looked up kegel exercises and tried them ( when I pee I can stop my stream) but I don't know how to really do a good kegel exercise without sitting on the potty. Are there any websites I can go to to help with this or any advise you ladies could give me ? I would really like to get my pelvic floor muscle to become stronger. Please help!!