sending Parameters in reportings

Question

hai 2 all


i have created 2 reports in ssrs .

1st report is select * from Categories
fileds

categoryid ----categoryname ---categorydiscrption

2nd report is select * from products where fkey_Categoriesid=Categryid

now my question is
 how to pass the perameters from one report to another and how to use that perameters


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if we onclick at categoryname..then in the subreport the related products of that category hav to display..how to do that.?