Marcelus' Potty Progress

Marcelus' Backyardigans potty insert came in the mail today and so he's sat on the potty a couple times today but has not gone, even after pushing...He continues to take his diaper off if he needs to be changed when he has no pants on. I tried to have him drink a sippy cup full while on the toilet to help but he didn't drink much of it anyway. We'll keep trying. It's great cause I'm honestly in no hurry,...I just want to put ideas in his head.