That PM66 board is pretty simple. You have to get the software on your PC first which can be found here:
http://pm66.software.informer.com/1.2/
You run the software, plug the board into your USB port. If you don't have an extension cable it can be a bit tricky to get a proper connection to your USB port if you have the double sided tape attached to the board. Just make sure it's pushed in all the way. In the software, click "Check board" first. This will let you know if it's plugged in properly by telling you what board is connected. Change the voice output to DAC for ext amp as that will give you a better sound. Leave the trigger function at default which should be One Shot Retriggerable. Where it says "Key", that is the button that corresponds to each button i.e. K1, K2, K3, K4. So if you want to program the first button to play a sound, select K1 under Key, press the little drop down arrow next to the first line under Wav...Mute and select New Wav... That will open your browse option to select your wav file. This board can only use wav files so you have to make sure that you have your sound files saved as a wav first. Do this for all 4 buttons and follow the steps in your manual to set the LED to flash or stay steady or to stay turned off for each sound depending on your preference. I have found that most wav sounds are best left at 8K as some don't play right at anything higher than that. When you are done, press PM66 and it will start flashing your module. When it's done it will pop up a window to save again or cancel, so you just click cancel, close the program and unplug the board. The attached speaker sounds very tiny but if you plug an external speaker in there it sounds pretty good. I have one of those and the ony thing I might change is the length of the wires going to the individual buttons as they are somewhat short. Hope this helps.