Use a clicker, it is excellent for teaching the weave, start with three poles, lure him in with food in your right hand, lead & clicker in left, as his body turns as you lure him round the second pole click, then feed as he comes out of the third. Do this until he does it without being lured, it usually takes about 8 short sessions, then moe on to six..
Another way is to set your poles apart at an outwards angle, and get the dog running through gradually moving the pole in, this also teaches the dog to move its body and weave.