Creating a function to simplify a more complex function

Greetings. I am a mid-level sort of Excel user, but I don't often create my own functions. I'm familiar with VBA for Access, but not for Excel.

Anyway, I don't know if this is possible, but I have a formula that I'd like to make into its own function. I've tried looking up how to do this, but I can't find anything.

The formula:

=IF(AND(ISBLANK(A1751)=FALSE,ISBLANK(B1751)=FALSE)=TRUE,IF(ISBLANK(A1750)=TRUE,A1748,N1750),0)

What I'm trying to do is make it so that rather than copying the cell again and again to where I need the formula, I can just create a new function, called FldPos, that will allow me to type "FldPos()" into a cell and have it behave as though this formula is in the cell (excelpt with relative cell references rather than specific ones

Is that possible? If so, how can it be done?

Thanks for any help anyone can give!