For most systems, you shouldn't have to use the command line to install wireless drivers, you should only need to do this if your wireless card is not supported or there is some unexpected issue.
As mentioned in another answer, you should be able to go to Open System Settings -> Software & Updates -> Additional Drivers, and there should be the option to install the wireless drivers for your system.
This is the recommended action, however if you're unlucky the option may not be there or it may still not work after you've installed it. If this is the case, then you'll have to resort to installing a driver manually. We can offer help with this though, we just need to have some more specific information, for example what wireless card you are using and what version of Ubuntu you are running.
To find out what wireless card you have (as per these instructions):
Open up the command line by pressing CTRL + ALT+T
lspci -v (or
lsusb if you're using a wireless card connecting via USB). You should get a list of information. Look for entries mentioning 'wireless' - this should tell you the make and model of your wireless card.
Now you're equipped with that knowledge, a quick search via Google or this site will normally provide you with information on installing the appropriate drivers. If you get stuck at this stage (either from lack of information or confusing instructions etc) then I suggest you edit your original question with details of your wireless card, or maybe even delete this question and re-ask a more specific one.