creating rule to adjust fields..

ok.. first of all..

I'm a complete Excel newb..
secondly.. I have no idea how to compose a proper topic title for my problem.. so I hope it makes sense..

I want to do what I've highlighted in the image attached...

it might be super simple.. but I have no idea how.

well, there's alot more I want to add, but this is a start, and will let me get on with it.

hope you can help!