Starting at the top of the engine--there should be a short lever attached to a rod that goes inside the valve cover. There should be a lever for each cylinder--in you case 2. These should be attached to a rod that extends back through the dash and that is your compression relief. Pull it to release the compression. It will return to normal position when you release it.
On my 2210D, the rod for the compression release that comes thru the dash needs to be rotated not pulled. Rotate it about 90ー anti-clockwise. If you can not rotate it, you may have to "exercise" the connection atop the engine.