In addition to the two forums toMACsh gave you, there is nothing like practice and experimentation. Excel and Numbers are both very powerful spreadsheets, and I have been using them (or the predecessor, Lotus 1-2-3) since the 1970's when Lotus first appeared. I'm by no means an expert, as there are many commands I never use, but typically the help in the app itself is sufficient to set me on a path to a solution. And in Numbers, the help is in the menu system. For example, all formulae start with "=", so as soon as you type in an equals sign in a cell, the formula window will open on the right of the spreadsheet with all of the possible options shown and an explanation of the current one selected below that. So all I did for your problem was to think through it in that you wanted an IF something THEN something, OTHERWISE something, so I clicked on the IF function and just below it was a very clear explanation of how it worked. From there I just worked to the simplest implementation, which is what I gave you. So, go play, experiment, see what things do. You can't break Numbers by doing that.
EDIT: One tip is that I turned your IF around so that I didn't have to do as many statements. Basically, if the field was zero, you wanted nothing done, but if it wasn't zero, you wanted something done. There is a solution using ABS function, but it's much more complex. Always go for the simple.
