<font color="blue"> (What equipment do i need?) </font>
To do what? If the wireless signal is not encrypted, there is precious little equipment that can help you. The best you can hope for is to understand the vulnerabilities and use a lot of caution in what you write or post on line.
In particular, financial accounts, SSNs, etc. should never be sent in a plain text email or through a Browser that isn't using SSL (secure sockets layer). Look for URLs starting with HTTPS when the browser makes a secure connection.
Be aware that some sites will send back the secure information in a plain text "confirmation email." These people are idiots, but as my wife likes to say, "Idiots abound."
Since you are connecting to a known WiFi hotspot. It is pretty well guaranteed that your data will be intercepted and logged by someone at some time. The war driving hobbyists will certainly do it, and I think it is likely that nefarious types will too, from time to time. Whether they can get anything of use to them and harm to you is a matter of how careful you are, and to some degree, luck.
BTW, I am curious how the sign up procedure worked. How does the truck stop know you are using their system, and what information did you have to provide? Did they ask for the MAC address of your wireless card? Did you or someone else configure or reconfigure your wireless connection? Did they provide a fixed LAN IP, something like 192.168.20.123? Are you certain it's not encrypted?