Doing a for loop with vbscript is extremely easy. The example below simply loops from 1 to 12 and displays the number on the screen. Simply put you start with the first line and set a variable equal to your starting point - in this case 1 and then you have the word to followed by the largest number you want to loop to.
After the first line you are in the loop and the current value of the variable is 1 to start so it will output
1
2
3
...
The end of the for loop is the next statement which tells the loop to increment count by 1 and do what's inside the loop again.
<%
For count = 1 to 12
Response.write count & "<br>"
Next
%>