depending on the style of belt, on the alternator belt there is an adjustment just below the slider holding the alternator, you just simply tighten it until belt becomes tight.
Sepentine-replace tensioner,v-belt, adjust accessory and tighten.
there is a belt tensioner pulley that maybe is not working correctly
You can do that by replacing the tensioner
the belt is automatically tensioned by a spring loaded tensioner.
The belt has an automatic spring tensioner and can not be "tightened".
this question should be under dodge automobiles
look in the instruction booklet
Its a lap belt.
Tighten it or replace it.
Very.
The alternator will move in and out to tighten the belt and the PS pump will do the same
replace the spring loaded belt tensioner as it's the only thing that will keep the serpentine belt tight.