Most of you who do photo editing will know this so if you can add anything please do.

I showed you the negative to photo fix from Dotty's machine yesterday but all you need is a half decent photo programme.
In Paintshop Pro go to adjust/colour balance/negative
In Photo shop go to image /adjustments/invert

For other software just have a browse you should find it
Just one click job done, depending on the state of the negative you may need to do a little adjusting or resizing.

Some of the scanners with all the bells and whistles actually scan and convert negatives and slides

Here are a couple of before and afters as requested. They need a clean up of course