Hi moticha,
First of all, I would suggest you to upgrade to 12.5 version since it is the newer release.
Either way, here are the steps for the backup:
0. Add the appropriate licenses to the Backup Exec Media Server.
Go to tools --> Install Options... --> Enter the licenses you have bought.
1. Install the agents to the remote computers
Go to tools --> Install Agents.... --> enter the appropriate information (IP, Domain, Username and password) and this will install the agent to the remote computers you want. If you DO NOT have an 2000 server, you DO NOT need to select the Advanced Open File Option (AOFO).
2. After the successful Installation, go to the Job Setup and create a new Job.
Select the servers/workstations you want to backup, enter the appropriate credentials if requested, and at the end schedule the backup to run every day.
Hope that helps.
Regards,