Display error to user if fedex shipping error?

Hello everyone!

If there is an error during the Fedex quoting process, I need to display an error message to the user that says something like...
"Please check your shipping address for errors"

How can I do this?

Any help is greatly appreciated!!! Thx!

Any suggestions on what to do?

Display that as a general instruction, to check it now and at each stage in the proceedings.