the oil drain plug is on the passenger side of the drain pan
Should be a drain plug at radiator either in rear or bottom
Either at the bottom or the rear of the radiator
If you cannot find the drain plug located on the oil pan, in plain view, you are not qualified to change your own oil. Pay someone to do for you.
On the oil pan. Crawl under the car and look for it. If you can't find it then you are not qualified to change your own oil.
on bottom of engine toward the passenger side
Open plug at bottom or rear bottom of radiator
The bottom of the oil pan,,,it is a 15mm
you change the manual transmission fluid in a '99 cavalier simply by removing the transmission drain plug and allowing all the fluid to drain then replace the plug and refill with Syncromesh transmission fluid(that is the fluid recommended by Chevy for use in your transmission) It should take 2 quarts.
There should be a radiator drain on bottom right side. turn it until it stops then pull out on it.
drain and remove the fuel tank. its grouped with the sending unit under the bung hole.