River Fishing

I said i would be back!!!what have i let myself in for i have entered the wonderful world of river fishing. when i fish still waters i can cast relax and wait. i fish the river the fly goes one way the line goes another and it all seems in the lap of the gods where the current takes the lot. i cant get my leader to sink and my fly is constanly dragged under by the current. any advice anyone i’m determined to catch one of those wily wild brown trout. please help