Any help is appreciated .

So I decided I would buy a peavey head that is 120 watts . and I found a 2X12 cab for it . The cab doesn't seem to have any brand printed on it but it has 2 peavey 1290 speakers in it . The seller said they are 75 watts each . I'm assuming I can use the head on this cab , but I don't know because I'm a total newb to heads and cabs . I've always used combos .

is there anything in specific that I need to do about hooking the cab and head up ? I know the head has an adjustable ohm switch , so what ohms would I have to set it to ? I googled the peavey 1290 speakers and I believe they are 16ohms each ? Correct me if I'm wrong . But that doesn't really help me because I still don't have any idea and I rather be sure than to blow something up .

Take off the back and read what is actually printed on the speakers and how they are wired. Post pics if you are not sure how to tell Series vs Parallel wiring.
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Ah yes the old Peavey labeled Sheffield 1290,  They were OK I guess,  had the same reputation as the old peavey amps,  Sound like crap but damn near bullet proof and lasted forever,  Gotta love the old Peavey stuff.    and yes 75W 16ohm, So here's the thing with speaker ohm/resistance, you can go up but you cant go down, The thing with amps is they need to see at least the ohm they're rated for,  less and bad things happen,  So in this case we know we have 16ohm per speaker, we could like an idiot I suppose wire them in series and make the pair 32ohm, but that's only something an idiot or metal head would do,   So what we do is set the amp to 16 ohm, and even if an idiot did wire these speakers up to 32ohm the amp still sees at least that minimum 16ohm,  Granted this will sound like crap but you wont need to worry about letting the magic smoke out of your power transformer,  Most Idiots, er I mean metal heads just set the amp at 8 ohm with speakers at 16 ohm for that annoying pushed sounds like crap thing,  The other ones set the amp at 16ohm  with cabs rated at 8ohm and think that smell of magic smoke is someone burning a blunt and looking to get a hit ,  Or at least until the amp shuts down forever, 
I decided not to buy the cab. I realized after asking that the speakers weren't considered very good. Even though the 2x12 would be only $75. I found a 200 watt 2x12 for only $25 more, and it seems to be easier to understand as to how to plug it in lol. 

The 2x12 was all one color with no information as to how many ohms it is or anything. I think it was custom made because those 1290 peavey speaker I believe came in 4x12's. The cab was in pretty bad shape too. So i'm passing on this one