So there is a lot of variables here. I'm not a great catfishermen, but I have some experience
I personally have a cheap combo that is dedicated to bottom river fishing. If you currently have a rod with a lure rating up to 1.5 or 2 ounces you could just use that. I bought a ugly stick catfish rod combo for $50 that is rated 1-3oz lures.
For the rig I only run a Carolina rig. (there will always be debate about type of line) I put 65lb braid mainline to a strong barrel swivel. On the mainline side of the swivel I have a 1.5-3oz no roll sinker depending on depth and strength of river current. Just like bass go as light of a weight as possible while relatively keeping it in one spot. Than I tie about 18 inches of 30lb mono leader from the swivel to a 6/0 or 8/0 circle hook. I use the snell not on the circle hook
The bait- if your state allows fresh cutbait from the water source you are fishing that would be the best. Sunfish, shad etc. Cut it into big pieces an put it on your hook. If no cutbait available us chicken liver, hotdogs, frozen shrimp, SPAM as other options
Location: Catfish are ambush predators kind of like bass. Find deep holes they could be hidding in. Find pinch points where bait fish move through. Best places would be below dams, around bridge pillars, outside parts of bends of river, where creeks or smaller rivers enter main river etc.
Get your rig, get your bait, cast it in, put a bell on rod tip, grab your beverage of choice, sit back and wait. Don't sit in one spot for hours if not catching, but have some patients as catfish will be on the move during their feeding times