Can someone help me write a macro?

Hello,

I have a large database of information (inventory). The datbase is constantly having rows added and deleted.
In column (1), there over 100 different items (string).
In column (5) I want a result dependent upon the value of column (1) (string).
When items are added to (1) I want it to update (5) automatically. If row is empty, then stop.
I understand the if,then. else feature...however, I am getting stuck on everything else.
I want the macro to run and save the result.