What file format is the movie in, if it is AVI or anything other than Video Compliant VOB files you need to convert it with Nero Vision Express. Basic Guide here.
If after your conversion the file is bigger than 4.3g which is what you can get on a standard DVD5 disk, you will need to compress it using either Nero Recode or DVD Shrink and then you can burn it using Nero.
If it is an AVI file you will need to convert it if you plan to play it in a standalone DVD Player, unless you have a DVD player that plays that format file. Read the guide on the above on using Nero Vision Express to convert and if the file needs resized after the conversion then use Nero Recode or Shrink and then burn that output file. If it does not need to be resized then just burn your output from NeroVision with Nero.
Its a AVI which means it must be converted before you can burn it onto a DVD, unless you have a player that is AVI compatible, if you do have a AVI compatible player you can burn it without conversion (burn as data DVD in Nero).
You have a few options, you can use Nero Vision, WinAVI, ConvertXtoDVD, ect.
My prefered way of doing it is with ConvertXtoDVD, theres a really good guide here:
