Find folder on network drive, based on username using bash shell in Automator.
With the information provided, I think the following should work (screenshot follows):

Run Shell Script
echo "afp://192.168.0.115/foto/"
Ignore input  

Get Specified Servers  

Connect to Servers  

New Folder
Name: Backup
Ignore input  

Set Value of Variable
Variable: Destination  

Run Shell Script
echo "/Volumes/foto/$USER"
Ignore input  

Copy Finder Items
To: Destination variable (drag the "Destination" variable from the variable list to the "To" menu)
Check "Replacing existing files" if needed.  

Variation for Incremental Backups

If you want incremental backups, you could replace Copy Finder Items with New Dated Folder, also setting its Destination to the Destination variable, and setting the "Action with passed items" option to "Duplicate passed items to the new folder". Make sure to enter something in the "Name" field, otherwise it won't work. To keep the backups listed in chronological order, you can set the Format to be Year-Month-Day and check the following options: "Leading zero for day", "Leading zero month", and "Month as number".