Question
I am trying to re-certify one of my users because his certification expired.  I don't know how to re-certify him since it is expired, do I make a cross certification?  IF so, how do I make a cross cert.?  I've never dealt with certifying users, and now I have one that is expired and the user hasn't been able to check their e mail in about a month.  Any help will be greatly appreciated!!! 

Answer
If the users certificate is already expired, the user need to make a save id copy and send it to you using any other mail account, another users mail, on cd or another way. 
1. User does: File/Security/User security, then on the Basic tab Renew button. In next window Export ID button to create save.id file.
2. Then user must send you this save.id file
3. You in the Domino Administrator must go to last tab, open Tool toolbar, click Certify button. Choose your certification server (eg users mail server) certification ID file (organization or organization unit, you want to certify the user with), click OK, select save.id, you have from your user, add certification details (expiration date etc).
4. Send the certified save.id file back to your user.
5. User need to open users security dialog (File/Security/User security), go to Certificates/Notes Certificates tab, click Get Certificate/Import (merge) Notes certificates and select the save.id file you certified in steep 3.