I made birthday cookies!

I made the soccer ones for a birthday party and the cute dinosaurs more recently for fun! I still have a lot to learn and am curious if anyone has recommendations for any online classes or YouTube channels that are good, or just some tips.
I really enjoy baking and was even considering making it a side business one day if I build more skill!
How long did it take to build the skill and technique to sell cookies and do mini a business?
All advice welcome and super appreciated!!