a little starter confusion. please help.

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what wires go to my starter on my 240.

theres two threded prongs and a plug in. the plug in is yellow/black. one prong gets a black/red power supply and the 2nd prong is hooked to the starter am i correct? does it matter witch prong the power suply is put on? and are there any grounds that need to be hooked up?

i did a dohc swap into my 90 240 and i cant get the starter to turn. its a new starter and the battery has charge. not every single one of my grounds on my engine r connect yet. can that do it too? cuz all the grounds work as one full system together? idk. alittle help plz.