Paper tray - feel the underbelly of the printer from the tray compartment. Papers sometime get snagged right before they get pulled in.
Check Front panel - the cartridge is easily slide in our out. Be gentle.
Back Panel - There are two problem areas. To reach them you will need to remove the roller piece. There are two small gray levers that are engaged to hold it in place on either side of it. Gently pull them up into the disengaged position, then remove the rollers.
You will find paper either stuck in the lower portion where it pulls paper upwards or crunched up in the roller itself. As well its not uncommon to find paper jammed in the upper deck of the back, there is a movable flap that you can reach underneath to dislodge the paper.