hello tomrivers and welcome to these forums. You'll find many helpful people here and a lot of useful information. Make sure you purchase Nicholas's excellent User Guide and ReaMix docs too. Worth their weight in gold.
Distribution:
http://forum.cockos.com/showthread.php?t=27999
User Guide:
http://forum.cockos.com/showthread.php?t=6107
ReaMix:
http://forum.cockos.com/showthread.php?t=21309
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ReaSynth should generate the audio when it receives the MIDI Notes and no you're not missing any plugins or MIDI drivers - but plugins are good to have
Try loading this trivial project file and see how you get on:
-- click the link and save the Zip file
-- unzip the file and place the .rpp file in your Reaper pojects folder (or drag it into Reaper)
HTH