Just download the full ISO form here.(offical downloads)
And burn the ISO to yur SD card (Minimum 2GB required) Look- Here is some more help.
I am not sure why and form where you got that self installing version? weird ...
Then- if you are using Windows 7 you can share your wired internet from your computer using your WiFi card in adhoc mode- (Not all WiFi supports this)
In the most extreme case- If you got an Android or iPhone- There is an option to use your 3G/HSDPA as a Hotspot for all your Wifi Devices.
But there is also a way to share your Wifi via LAN (using crossover LAN cable from Point-to-Point!)(or a switch in the middle, using 2 cables Point-Switch-Point) But you have to set static IP's all over the place.