First off, welcome to Debian!
If you haven't done so already, I strongly recommend you read the installation documentation at
www.debian.org . This should be the starting point of everyone wishing to install Debian.
There are several ways you can build your system. The 'default' way you should have already come across during the netinstall. It's the part which asks you to download and install packages. This can be daunting to new users, however, because it involves using the aptitude package browser. There are other, better, ways of completing a netinstall.
Personally, I wouldn't bother with your dvd .iso images. There is probably a way you could mount and make use of them, but you will make life much easier for yourself if you follow an existing set of instructions. My recommendations here are -
1. The 'Debian Configuration Post-Install' by macondo, posted in this forum as a sticky thread. Highly recommended
2. Debian Survival Guide -
http://www.togaware.com/linux/survivor/ .
3. Debian Desktop Setup Guide -
http://thegoldenear.org/toolbox/unic...ian-sarge.html
I have found all of these 'unofficial' sources extremely useful in setting up Debian from a netinstall CD.
Good luck!