adjust applescript that currently returns the correct echo command and then execute the echo command in terminal (osx)

i am trying to create a mac application that can print in the dock menu. to do so I need to drop a file, get its path and execute the "lp" command i can get the script to echo the correct terminal command, but i can't figure out how to get the script to execute the terminal command. i have attached where i am up to, to date.