参考excel中基于变量的范围？

I am trying to set a macro that will, at some point, end up setting a cell to a sum of a few cells. The cells that will be summed, however, are variable, and based on other things (and will change on each iteration of the macro). I have coded the macro such I will know the row that the cells are on, as well as the column of the beginning cell and the column of the ending cell (ie. perhaps A600 to A606 will be summed). However, I have set these column and row assignments to variables, say Y, Xstart, and Xend. How do I have the sum select these ranges, of the cells are purely defined by variables?I am trying to set a macro that will, at some p