Replaced the Serpentine Belt, but cannot get power steering pump belt to go on pully, even after loosening bolt. Do I need a mechanic?

IF you have a serpentine belt it's not a matter of adjusting the power steering belt tension because it's done automatically with a serpentine belt tensioner.
OTOH, if you have a separate V-belt you'll need to loosen the mounting bolt/nut at the bottom of the steering pump and the adjustment bracket then tighten the belt by moving the adjustment nut to tighten the belt.
You might be able to google a video of your particular engine power steering belt adjustment.

Tighten your serpentine belt.

you will need to loosen all bolts in order for it to move but the pivot bolt will be sitting in a metal channel on the alternator bracket

you will need a thirteen mm socket, rachet, and extension, the power steering pump pully has three holes in it to losen the pump,and then theres and adjuster screw to loosen the belt, all the bolts are 13mm

BELT ADJUSTMENT
MANUAL BELT TENSIONER
Loosen rear mounting bolts of idler pulley or power steering pump (if equipped). Loosen power steering pivot
bolt and lock nut (if equipped). Turn adjusting bolt to tighten belt to specification. See BELT ADJUSTMENT
SPECIFICATIONS table. Tighten bolts and lock nut to 20 ft. lbs. (27 N.m). For serpentine belt routing, see
For the routing just draw a picture befor romoving the belt. There are 4 different routings and I don't have enough info for yours. Without the proper tool the adjustment spec won't do you any good so before you take off the old belt get a feel of how thight it is and try to match the new one. best thing to do it make it loose enough so it squals when turning the steering
wheel to the extream or stop then tighten the belt little at a time till it doesn't squeal then just go a little bit more. If the belt is too tight it will wear out bearings in water pump,Alt, pullys ect. If its too losse it will squeal and wear out the belt so take your time on the adjustment.

Really don't need a diagram. Loosen the slide bolts on the power steering pump. loosen or tighten the pump by turning the jack screw (long transverse bolt) under the pump. Once the belt is tightened up, lock down the slide bolts and you are finished.

If the tensioner can be moved by hand the lock down bolt is not doing its job. Try to tighten the bolt with the belt pulled tight and then release. If the belt loosens the bolt is not working as it should. Make sure theres a lock washer (split lock washer) between the bolt head and the post.

Should be the pulley underneath the power steering pulley. Loosen the nut, then back the bolt down the loosen the belt, tighten the bolt to tighten belt.

the 4.0 didn't come with a spring type tensioner if look under the p/s pump there is a jack bolt hooked to a idler pully loosen nut on front of pully and lossen up the jack bolt till you can get the belt off

3 bolts should be holes in the pully too go thru with an extension if their are no holes in the pully then you nee a power steering pump pully remover it can be rented for 5.00 at auto zone