ok, the lense is notched, with small peices of the frame that click into the notch. the key is to pull the top of the frame up away from the lense until it releases. from there you can pull the rest of the lense out safely. then, insert the new lense bottom first, aligning the notches so they clip in, then pull the top of the frame over the top of the lense, line up the notches, and squeeze them together, and there you go.