How to write user defined function for Index and Match

Hi I am quite new to this VBA programming. What I want to do is to convert the following formula in excel into a user define function.

The formula in excel is like this : =INDEX($X$3:$AL$40, MATCH(1, INDEX(($V$3:$V$40=C3)*($W$3:$W$40=D3),),0),MATCH(E3,$X$2:$AL$2,0))


Can someone please help me or give me some example of how the VBA codes will look like?

Thanks

OK, the obvious question is why?