Rename files using cmd ren command

I'm a newbie at this but have spent the afternoon searching your forums. While there are several posts about the ren command i can't seem to get mine to work?!

I would like to change:

A22-7000
A22-7001
A22-7003

to:

A24-7000
A24-7001
A22-7002

I opened the cmd window in the folder location and tried various forms of the following:

ren *A22 *A24

I know this should be easy but it's been driving me insane! Also, if anyone has a link to good tutorials where I can learn this sort of this that would be great!

Thanks!