how to import xls file from qc

[frebuffi]

guys,
how can I import xls file from QC if i had many xls files
attachted in the test set ? I want to do a "function"(so then i can associate that function to all the tests) with a parameter in all tests so when i tell qc the name of the parameter the function will import the file in the test if the name of the file exists.
if not the function has to return a message, "not posible to import file"

Thanks!