You cannot tighten the belt it has an automatic tensioner on it.
But before you go ant replace it here it something to try.
Find the location of your Tensioner Pulley and your Idler Pulley then with a spray lube and the engine off spray the center bolt of ONE of the pulleys. Then start the vehicle. If noise is gone for short time then the bearings are going back and you will need to replace that pulley. If noise is still there then turn vehicle off and spray other pulley in same manner and restart if noise is gone for short time replace that pulley. While doing this also watch the tensioner assembly for excessive movement. Also when was the last time you replaced the belt an old worn belt can cause the sqealing also.
If you need diagram will need more info on you truck
Is it a 1500,2500 etc and is it 4x4 or not and engine size in liters.