Novice rider

So I’m still trying to learn to ride my man. Usually when I get on top, he doesn’t mind putting his penis in my vagina and then we get going. But I’m pretty sure he’d like it if I could give him full service - put his penis where it needs to be and all. But I haven’t been able to put it in myself. He let me try but after a few tries I think he got impatient or something and I was getting scared that I may have hurt him. Anyone have any tips to get it in? I tried getting him hard first but without any luck.