Yes you need to open up 4 separate instances of MFME v5.1, not v5, 5.1. Open the first one, then you need to enter your i.p address. To do that go to file, preferences and hit find by IP Addr, if your firewall says allow, you should do. Then load in the top box and wait for it to finish initializing.
Then open up another 3 instances of MFME v5.1. You should need to go through the I.P business again. In each instance you should open up one of the bottom machines open in it.
Drag them to line them up underneath the top box. if you press f1 it will get rid of the title bars, esc will bring them back.