You just need to setup internet sharing from your computer, since that looks like a usb 3G type internet device. Depending on your OS, many different ways to do it. windows would be the simplest. just follow the wizard.
Pretty sure if he is plugging modem into his machine directly he will need another radio (or use the ethernet and connect his ant wired).
Simplest thing would be to get something like this (
http://www.amazon.com/EW-7811UN-IEEE-802-11n-draft-USB/dp/B005CLMJLU)
and then setup internet connection sharing in whatever OS you are using.