Including cells that are highlighted in a formula

[Robin]

I have a strange requirement maybe, but I do a budget spreadsheet on which I
highlight items that have cleared my checking account. I would like to be
able to write a formula that sums only the cells that are highlighted a
certain color. Is this possible?

 

[Robin]

let me clear this up a little. I don't really mean "highlighted" as in I
highlighted them with a mouse. What I mean is formatted with a fill color.
sorry for the confusion.

 

[Robin]

do I have to have an add-in or something to do VBA in Excel?