Single Boot, Ubuntu 13.04 only, can not re-install with DVD

Single Boot, Ubuntu 13.04 only, can not re-install with DVD

I wanted to re-install 13.04, but when I insert the DVD it does not
recognize it... and it just boots up as usual... it does not take me to
the install DVD. I put in a boot repair CD... and that is not recognized
either.
I am very new to Linux... so I'm lost.
I wanted to re-install Ubuntu 13.04, because my boot is full, and only has
2.64 MB of storage left. I cannot add or remove software, as they fail due
to this error. My intention was to re-install 13.04, use gpart to increase
my boot drive space, to avoid this problem again.
Any help would be greatly appreciated.