Your first step is to make sure that the wireless drivers are correctly installed. Without this step, it is impossible to move forward.
Once you've got that done, this next step is comparatively easy: getting the access software installed. Of course, you will need access to a wired Internet connection in order to download the software, just as with installing the wireless drivers.
Most wireless network software is not designed purely for wireless networks, but also to handle wired networks and other types of network connections: so chances are, whatever you end up installing will also be able to multitask.
Fair warning: Not all of these wireless access software options work on every single distro: you might have to do a little research on your own to see if they're compatible. Also, some wireless network managers do not work with every single wireless driver, even if you have them installed correctly.