How to change blades. I was abe to remove the bland, but how do you get it back on?

If you are dealing with a 76076-010 clipper, this is how you remove and replace the detactable blade. There is a small gun-metal colored bar at the very rear, just below the back of the blade. It pushes inward, in the direction of the blade. Push it firmly in and pull up on the teeth of the blade. It should pop upward. You can then remove the blade from the tongue that it sits upon. When you want to put it back, slide the blade back on the tongue, then, WITH THE MOTOR TURNED ON, push the blade down to its seated position. It will click into place. If the tongue has gotten pushed back against the body of the clipper, simply insert a screwdriver blade behind it and pop it back out so that you can slip the blade back on it.
Hope this helps you.

See the manual

I appreciate phischneide's solution, but no matter how hard I tried, the new blade would not lock into place. I tried calling Oster and to my dismay they have no customer service to help its customers. I have decided that the best possible solution is to get rid of the **** thing and to never EVER buy another Oster product. I suggest the rest of you do the same.