Beginners Exercise - Body Weight Squats
This is absolutely the BEST exercise you can learn to do and should be a part of your regular exercise routine. I talk about them a lot but you NEED to be doing these. If you have knee trouble, first make sure you are getting your but out far enough as you should not feel it in your knees. Make sure you are pushing down through your heals not your toes. Its awkward at first. Keep your back straight. If you still feel it in your knees get a kitchen chair to put in front of you to hold on to just to stabilize, do not use your arms to pull you up!
Here is a good video that demonstrates the technique:
Thats great! You want your legs to be sore the day after you do these. You will get to the point where you can do 20-100 every day and not be sore. If you are not sore you didn't do enough of them. Form is absolutely critical on squats otherwise you will hurt your knees and back, but done correctly the best exercise you can do.
Just envision yourself in a couple of weeks with a 100lbs barbbell on your shoulders and doing these. Here to help you with what you might look like:
You should also do some pushups (from you knees for now), crunches, and jumping jacks.