Using xargs with input from a file

Say I have a file with the following bob john sue Now these directly corrospond to (in this case) URL pattern such as http://example.com/persons/bob.tar, john.tar, sue.tar. I would like to take these lines and run them through xargs. I don't know what is passed to the command being executed though. How do I access the parameter either from the prompt (say I want to simply echo each line like cat f