My tube got a puncture and I picked buy new tube option .vs. patching. I bought 2 so I had a backup, I think it was 16 bucks.
Tools needed, 8mm socket and 4mm allen to remove nut in pick below, safety pin removed, not in pic below. 1.5mm allen to remove set screw in pic below behind the nut (1 on each side).
Gently pull front fork apart so you can slide tire out. I happen to ride bikes and already had the little tools to assist in getting tire off/on. Off you don't need, on, it makes it easier. Or you can just have your local bike shop do it when you go buy the tube.
Tube size 16" 1.50-2.25 if you order online .vs. taking to bike shop.
If you plan on doing yourself, a bike tech recommended inflating the tube some so nothing gets pinched which can cause another puncture down the road. Place tube inside tire, get rim with stem hole lined up and insert rim. work the bead around on 1 side, and the other side is where the little tire tool comes in handy. They are cheap, would be a good idea to buy and learn how to use in case your out flying and catch a flat, you can fix and keep on flying.
Hopefully this helps.