Make sure you have all the Restore options set then goto Advanced Options. If you want to redirect the restore set that up under Rename Data Sets (which is another can of worms). To restore to the same place it was backed up from just goto Subsets to Restore.
At this point all selections should say 'Default'. Select 'Include Files' (an include is exclusive, nothing else will be restored). Selection List Options will popup with a blank list. Hit Insert (on the keyboard), select the Namespace (use LONG if you're unsure), then enter the full path of the file you want restored (where the file existed when it was backed up). EG,
VolumeName:/parent/child/file.ext
Since the target server was selected before you went into the Advanced Options you do not specify the server name.
Now hit Esc 4 or 5 times until you are asked if you want to submit the job and select Yes. The job will run pretty quickly on a single file restore, remember that SBCON doesn't refresh it's screens worth a **it and you usually have to exit a screen and reenter it to see a refresh.
Good Luck and get that goat liver ready.