Cms help/suggestions

OK, here’s a silly question-

I have a client who wants a custom cms for a sports website, however, I really don’t know how to create one myself. What I would like to do is design everything myself (including the html/css - that much I do know how to do) and be able to use some kind of software to allow my client to add and edit things like player rosters, divisions, stats, schedules.

Is this even possible? If so, any suggestions?

Thanks.