User friendly summarising

Hi Guys,

I'd be a moderate user in the sense that I have written some VBA codes but I have a tendancy to copy and paste, editing to my needs. This one has me stumped though.

I've an excel document attached. Basically theres an array of data (in the data tab - simplified here). On the summary tab the user can enter either of 2 inputs, each with a seperate macro.

For input one the user enters a start row (X) and an end row (Y). The Macro then sums up the column to the right of this from rows X to Y-1, i.e. sum the number corresponding to row X down to the number correspoiding to the row above row Y and return the value.

For input two its sort of the opposite. The user enters an end row (Y) and a number. The Macro then sums all numbers from row Y-1 backwards (i.e. Y-1, Y-2, Y-3 etc...) until it reaches a value greater than the inputted number, then returns the corresponding row number.

Any help would be much appreciated. If I got the basic code for the example attached I can edit it and implement it to my data set.

Thanks
Brendan