Remove the two screws on the front of the cluster. The bottom of the cluster has 2 tabs on the bottom, so you'll need to pry it from the top. Once you've gotten it loose, disconnect the circular harness plug, and the two wire leads that are held on with two nuts. Then you'll have to remove the speedometer cable from the back. It is held on with a single spring steel fitting. Lift up on the end of the fitting closest to the back of the cluster, while simultaneously pulling the cable away from the back of the cluster. You can rock it back and forth and twist slightly to help get it free.
Then your cluster should pop right out.
The lightbulb holders are twist lock. Just give him a twist, and they should come right out. And then, simply pull the bulbs out of the black plastic holders. When installing the new bulbs, keep in mind not to let your bare skin touch the glass or it can cause premature bulb failure.
FWIW - While @MScruiser process is correct, there is something that you need to do before you start the above. Either disconnect the battery or separate the fusible link at the battery. If not, you will possibly create a fireworks display in your dash and could short something out.