A great resource to hit for help on Video Editing and Conversion or other questions is
VideoHelp.com
Just keep in mind that not all free (or even payware for that matter) software for working with Video is even remotely good.
If you do decide to try some of them listed on the site, it will be a trial by fire kinda thing.
But beyond the software that is listed, there is a lot of other great info for newbies to video/audio editing/conversion.
There are other sites as well.
Video editing is an art form and what works for one may not work for another.
I use several tools.....
If you want to create some decent DVD's, (this is not an editing tool) this is a DVD creation tool. You will ahve to research them to see if they will support or create HD DVD's ,,, but I do Recommend
DVDLab