There are two different types of memory in your Mac. There is system memory, more commonly referred to as RAM, and there is disk space. RAM is where the Mac works on data. Disk space is where data is stored for long term storage.
You are in serious danger of causing your Mac to die completely by running it with so little free space on your system drive. It is imperative that you start either deleting or move data off the disk drive. You should have 8 to 10 time as much free space at least at all times for OS X to run will.
A tool that can with cleaning up your disk drive is OmniDiskSweeper. It will tell you the files and fol,der that are using the most space. That will give you good candidates for deletion or movement.
System memory is RAM (those 2GB you mention) not hard drive space. If you have a lot of music - video and photos are other big items that may take up a lot of space - you can either replace your internal hard drive with a larger one or you can get an external hard drive and put your music library on it.
See this Apple article on moving your iTunes library.
Best of luck.