If the connector has 3 prongs, the ground pin should be connected to a metal part of your case. If the PSU has a ground connection as well, connect it to that.
Yeah, that's the connector I'm thinking of. IIRC on my 160W AC-DC HDPLEX it's a green wire.
To find that out, you can just search for the model number on molex website. Your particular ones refer to the housing and the crimp terminal. From what it looks like, a normal crimping tool should work, but the terminals seems rather large.
Hope that helps a little.
Sorry, I didn't realize it was that simple! That you pointed to them specifically helps a lot.