how to improve leg power??

Beginners shouldn't think too much.

Worry about advanced plyometrics after you can squat more than 20lbs.

If you have no strength then start to use basic strength exercises like squats and leg press. Some people get offended by certain exercises like leg press, but as long as you are doing squats as well it doesn't matter.

Once you are strong in the lower body then go for something more specific.

 

Agreed. They do recommend a good strength baseline before doing plyometrics.