Filling Cell Range With Ascending Numbers?

I have a button event coded to select and ultimately fill a range of cells with the intent of representing a timeline of payment periods.

Private Sub Timeline_Click()
Dim x As Integer, y As Integer, cell As Range
x = 1

[Code]....

The first row needs to be filled with numbers from 1 to the value of [D20]; E.g. if D20=10 then there would be 10 columns selected then filled 1 through 10.The second row needs to be similarly filled with ascending Y values; E.g. D13 = 4, D20=8: row 2{.5,1.0,1.5...}