Do you know how to use valve spring compressor?

If using a valve spring compressor to remove the valve springs from an already assembled cylinder head,

first lay the cylinder head on its side.
2.Use the valve spring compressor by placing the U-shaped portion over the valve spring retainer and the screw on the cylinder head to compress the spring.
3.While the spring is compressed, remove the value keepers and retainers.
4.Slowly release the compressor and remove the valve.
5.To use a valve spring compressor to install valve springs, first place thespring over the valve stem.
6.Install the valve retainer over the spring.
7.Use the valve spring compressor in the same manner as was used to remove thespring, but instead compress the spring down the valve stem and install thevalve keepers on either side of the valve.
8.Once the valve keepers are securely in place, remove the valve springcompressor.