When you want to add songs to iTunes, you don't have to add them one at a time. Instead, you can put them into folders and add the whole folder. When you do that, iTunes will automatically add all the songs in the folder to your library and categorize them appropriately (assuming they have correct ID3 tags, that is). Here's how you do it.
Begin by creating a new folder on your desktop (the way you do this will depend on what operating system you have, and which version. Since there are so many possible combinations, I'll assume you know how to do this). Then drag the songs you want to add to iTunes into that folder--these are likely to be songs downloaded from the Internet or copied from an MP3 CD or thumb drive.