Open it in Windows Movie Maker, and the video will automatically be split in a bunch of pieces, if you want to split any of these farther, you can.
Under the video screen are some buttons, including four arrow buttons. The ones on the outside are for skipping to the beginning and end of the clip. The two in the middle are for going frame by frame. Use those to find the point you wish to split your clip from, then push the split button (on the right, next to the one with a camera on it).
Then you can drag your clips down into the storyboard (at the bottom of the window). Once they're there, you can also drag them around to rearrange them.