Product review (5 stars): Beats a $50-$100 service call!  Not hard if you are patient.
An easy fix!  After about 7 years, our Samsung Dryer belt was falling apart.  Thanks to the internet, there is a video to show how to take apart and install the new belt.  My dryer is the gas version. You do not even have to unhook the gas (or the vent tubing) to change the belt!  Unplug the dryer, take the top off and follow the instructions to take the pieces off of the front.

Watch the video to see how the belt wraps around the idler pulley.  There are a few possible ways to install it, and only 1 right way so that the belt grooves are on the right side at the motor.  You have to do this by feel when you leave the dryer in place.  If you can get to the back, removing the access cover WILL make routing the belt around the pulley easier...but it isn't required.  It's the front of the dryer that needs to be disassembled to actually change the belt.

One caveat:  Be sure you pick up any pieces of the old belt that you find floating around loose.  You don't want them getting picked up and knocking the new belt off of the tensioner pulley.