How to add a parameter in a link

In a list page I have a column containing the typical link to another list page

For example:
"MyPage(4)" that goes to http://myproject/output/MyPage_list.asp?mastertable=dbo.Prj&masterkey1=462
How can I add a parameter to my link? I want to add a "&myparameter=1" so that the url becomes
http://myproject/output/MyPage_list.asp?mastertable=dbo.Prj&masterkey1=462&myparameter=1
In the code I see something like
<A {$MyPage_dtablelink_attrs}>MyPage{BEGIN MyPage_childcount}({$MyPage_childnumber})

{END MyPage_childcount}</A>
Where can I add the variable?
Thanks