If you've got the iso's under windows, then also download and install md5summer
.then get the md5sum file from the mirror that you downloaded from - print that off.
Then open/start md5summer, use the "create md5sums" facility, highlight the file and create - when it's finished its thing, compare the md5sum with the one you printed off from the mirror - if it's the same then great - if different, you're gonna have to re-download.
Once all three integrity checks are done, then open nero, close the wizard, just go for file>burn image and highlight the one that you want to burn.
Then just burn.
If you're still not sure, google for burn+image+nero+linux or something like that, I know there's a couple of small tutorials out there. But from my point of view, they only tell me with other possible settings I could use, and mine have always been correct as default.