Macro: assign value of x-y postion

Hi,

I need to create a macro which will give the cell of a co-ordinate a value of 1.

Basically I have two columns called X-Position and Y-Postion e.g.

X-Position Y-Position
2 16
6 9

So the marco will take the 2nd row 16th column in and assign that cell the value 1 then take the 6th row and 9th column in assign give the cell value 1 and so on...