Once you have configured both products, you need simply create a NFS or CIFS file share on the DXi and create a policy on vmPRO that directs backups to that share on the DXi.
The DXi appears as a file server on your network and vmPRO will write to any NFS or CIFS share available to it.
Please review the material available in the Resources link on the top of the banner of Forum V.
Logon to the VXi1000, assuming you've run the config wizard and imported your license etc.
Go to config - add storage there - note you will end up with an export similar to Q/share/nasshare(or whatever you called it)
Enable de-dup (because you can)
Go into vmPRO and click on configure, go thru the config wizard ;
click on storage --> setup your hostname as the IP of your VXi1000, device as quantum dxi, protocol as NFS, share as Q/share/nasshare(or whatever you called it) and click save storage
Then configure your backup policy to write to that location and you're set. Hope this helps.