Chris: You already have the latch - that's what is popped when you pull that knob at the rear of the door opening.
For something to actually lift the engine cover when you pull that knob, you need a gas strut to do the lifting.
If you do a search on here for "gas strut" or "Engine Cover Opener" you should find some past posts that cover it with DIY how-to instructions and part numbers for compatible struts. If not, let us know and we'll find the posts for you.