I understand your frustrations, completely. Re-installing Ubuntu may be one way to solve the problem. It may not be the best way, at least in terms of what you will learn in the process. It looks like you are running under Windows according to your ID area. Do USB sticks work under that? If they do, you may be able to make a boot USB stick to work from and / or re-install off of. I would first suggest trying to see if you can repair the system, which in the long run will be more beneficial to you. As you said, you don't know a lot of commands and there is only one way to solve that.
The first thing I think you will want to do is bring Ubuntu up to a terminal prompt. CTRL-ALT + a function key like F2 should do that for you. This switches between the terminals. If I recall, Ubuntu creates 4 terminals, with F1 being the system log console. There are also your graphic sessions starting on F7. Without Gnome, you will want to use a terminal.
After you get to a terminal, you can see if you have multiple partitions and what the space available looks like on them. You can use 'fdisk -l' or 'df' to do this. A note about the permissions. Ubuntu locks the root user, so you can't login as root. The normal way to execute root privilege is to use sudo (super user do) and your normal user's password. In other words, prefix the commands with sudo, e.g. 'sudo fdisk -l'. You may have installed everything in one partition, which is fine. The big question is whether it is the root (/) partition or the /home partition that is out of space. This will determine what action to take next.
If it is the root partition that is out of space, you will want to remove some packages. Since you are operating at a text terminal, the best program, to do this might be aptitude. It is a text based (ncurses) application and can be a little funky with the menus, but it can get the job done. You will want to search for packages that you don't think you will need or want and tell it to remove them. I believe after you select all your changes, you will need to apply them (G-command I think). Otherwise, from the command prompt you can use the 'apt' system. You can use commands like 'apt-get remove <package> or 'apt-get purge <package>' to remove them and make space. There is also a search feature, 'apt-cache search <package name>'. I would recommend consulting the Ubuntu wiki pages. They are very well written documents on how to do many things.
Note: again you will need to have elevated permissions to use this tool. Prefix the commands with sudo!
If it is your home directory, you should be able to simply remove stuff. I am not sure why this would give you a permissions problem, but if it does, sudo to the rescue. To remove entire directories of stuff you can use the command 'rm -rf <path>'. Be VERY careful with this one. If run as root (sudo) from the wrong location it WILL wipe out your system. Check twice and erase once. You can double check your location with 'pwd' - print working directory. Similarly, you can list the files with ls and use the argument switches -l and -a for a longer listing and for all files including hidden ones.
After you gain some space, you may need to reconfigure or re-install gnome. I would suggest seeing what the documents on this error say first. To re-configure a package, you can use the command 'dpkg-reconfigure <package name>' from the command line or use a tool like APT that I mentioned earlier.
Good Luck and if you have any additional questions, please post them.
i dont care if i loose everything on my computer just need it to work again 
