First off, welcome to the forum.
Second NEVER, I mean NEVER, refer to your Jeep as a "car". It's bad karma
. If you do it too much, your wheels will fall off.
Ok, seriously, your window tracks are possibly warped, or there may be a broken fastener allowing a track to move. Will the window roll right back up, or does it require help?
To get the crank handle off, there is a retaining clip with a sort of hourglass shape. You pull that and it the handle should slide off. There should be a plastic bushing/washer between the door panel and the clip.