The MSA 2012fc is fibre-channel, the 2012i was the iSCSI version and the 2012sa was the direct-connect SAS version.
If it is the fc version (it'll say on the controllers themselves) then you'll have to connect them via fibre-channel (or FCoE but that's way out of your picture I suggest) - and FC isn't the least-complex thing in the world, though I'm happy to help if you have specific questions.
Sam's right though that R5/50 is dead, has been for half a decade at least, please avoid for your data-health and sanity - 1/10 and 6/60 are the only games in town.
Edit - thanks for all your information so far, here's what you need to do.
Add a dual-port FC HBA PCIe card to your server - there are other manufacturers but I like Emulex (QLogic are very good I just don't have as much experience with them). There are different speeds you can get but as your 2012fc only runs at 4Gbps then there's no point spending money on 8 or 16Gbps card, but you may find that's all you can get - Emulex cards based on their '1105' chipset are very reliable. So you stuff that in the server, you then download and install the latest drivers and utilities from the manufacturer's site.
You also need to add in the 'multipath' feature in server 2012R2, this is important or your server will think the one LUN you've shared is actually two, one down each line!
Oh yes you need to cable it up - go from server FC port 1 to SAN controller 1 port 1 and server FC port 2 to SAN controller 2 port 1 - use 'OM3 LC-LC' fibres, that's all you need.
You then need to configure the array, once you're into the GUI you need to create an array of the disks using RAID 1/0 or 6/60, then create a LUN (logical drive) of whatever size you like, then you share that out onto the controller ports mentioned above as a particular LUN number (start with 1).
You can then go onto the server and go into the FC utilities and 'scan' the FC HBA, you should hopefully see the WWNs (world-wide-names, like MAC addresses for FC kit) listed, one controller per server port, and hopefully the WWN for the shared LUN. If this is the case you just go into windows disk manager and that LUN should be seen as a disk, so partition and format it - job done!
One caveat here, if you ever want to share a LUN between more than one client you have to jump through a lot more hoops, your setup is about as simple as it gets (hopefully).
Hope it goes well, let me know how you get on ok.