Good advice above. As a skater, the cadence that feels natural to you will probably be pretty low. Maybe 70-80 RPM. (If you do not have a bike computer but do have a watch, count your pedal RPMs for 6 seconds and multiply by 10.) There are good reasons to try to adopt to a higher cadence. Easier on your knees. Easier on your muscles so late in a ride you have more reserve left for that last hill or hour of riding. This will not happen comfortably overnight if you are like most of us. Higher cadences often feel very forced and unnatural at first. Seats are often less comfortable at higher cadences. (Meaning you may have to look for one that fits you better or fine tune the one you've got; a plus in the long run.)

Welcome to cycling! Hang in there, it's a great life.

Ben