Hi im lvl 66 and i have bought riding skill and 60%mount but cant use it?
my character is night elf lady : ) named kis.

This is what i've done to ride my 100% speed increase mount.
First when I was lvl 40, i bought the apprientice riding skill and a mount, but I couldn't ride it, so when I reached lvl 60 I went back to the mount vendor and one mount said I could ride it. But I am not sure if the same thing would work for you.

Please read the FAQ before posting stuff like this. This has already been answered.