Basic IF loop & commands for an entire column?

Hello everyone,

I've been googling with no luck.

What commands do I need to do the following..

Run the following through a column until there are empty rows..

.. Check each value, and IF the value is between -20 and 0..
Change the exact cell contents to -20.99
Change another column on the SAME row to a different value.

There are a few different cases (if it's 0 to +10) that require other changes.


OR if you want to see my exact requirements, I've attached the Excel file.

Thanks so much everyone,
Daniel.