First use this website to hear what the different instruments sound like on their own:
Listen to the first part of 'Airs by a Stream', on the Youtube video: 1'58"- 2'40"
Listen to the Pastorale: 4'55" - 8'17".
Listen to the marching music again from the beginning and see if you can pick out the double bass oom-pah - the percussion joins at 0'55". Also listen to the percussion at the very end - 30'45".