Potty Training Tips Anyone?

I have a 2 year old son and I am a first time mother. I'm trying to get him potty trained. When he was 18 months I tried a few times to sit him on the potty but he was terrified. I gave up and waited till he turned two so I could be sure he was truly ready. A month ago I was changing his diaper and he told me he wanted to sit on the potty. He has not been terrified of it since. The problem I'm having now is he's sittin on it but he won't pee in it. Can anyone help me get a routine going where I can time it just right, to where he goes every time? Thanks a bunch.