This tutorial will teach you how to animate objects in blender using keyframes.
Edits done in Blender:
Split the window of blender, in one screen you switch to Timeline and the other one stays in 3D View. Switch to the Pose Mode of the Armature. Set the time frame to your desired length. Remember it's frames, not seconds! Usually, there're 25 fps.
Press A so all nodes are selected. Make sure the time controller on the timeline is on 0. Press I > LocRot. Move the time controller 10 frames up (using UPARROW). Now rotate each node a little bit (not more than a few degrees) using R or double R (axis-free rotation). Press A so everything is selected. Press I > LocRot.
Repeat this until the time controller is on your desired animation length.
Now go on if you want to loop your animation (you usually will).
Now move the time controller back to frame 0. Click the downside arrow (that copies the current pose to the clipboard / buffer). Move the time controller back to your animations end. Click the upside arrow (this pastes the pose from the buffer). Now press I > LocRot again.
Make sure the cursor is over the 3D Window and press Alt + A so you can watch the animation.
Edits to the .xml file: