Here's a grossly similar one from Molex. It is open, and apparently the black part just tilts up. In all cases I have seen, a part over the cable swings up. When you re-insert the cable, it snaps back down to hold the cable. Do that carefully to be sure everything is aligned. Some have a latch on the side, others, just a fingernail under the movable part opens it. The Nikon D70s I disassembled was the latter type. The latch was brown rather than black. It doesn't take much force.
Be sure us wear ESD protection.