I am trying to clone a 2TB drive that has mac os x 10.6.8 onto a smaller drive but dont know what I am doing
Assuming your info is correct &amp; there is going to be room on the 250, this should be simple in a Pro.


Put both drives in the Mac Pro.
Boot from the one that works.
Format the other [just to be certain] in Disk Utility as a single volume, GUID/HFS+ [Don't name it exactly as the other, to save confusion]
Get Carbon Copy Cloner*. Paid, but demo available - It's worth owning.
Clone one to the other.
Remove the old drive. 
Boot to the new drive.
Change its name to that of the old drive
This will just fix anything that is using the actual volume name - it shouldn't, but it might be. You can skip this step &amp; see if anything falls over, if you want to separate the names long-term.
Done.


* Looks like you will need an older version - 3.5.7 from the bottom of this page - https://bombich.com/download