I have created Report in SSRS-2008
using Tablix Data region.
My dataset returning 1000 rows. When rendering into pdf i have to display 20 rows per page
Go to the properties and find:
Report, Page--->InteractiveSize---> Height
Change the height properties by 5.5 and you will be able to show 20 rows per page.
First result on Google for "SSRS Items per page" was: http://www.sqlservercentral.com/Forums/Topic490774-147-1.aspx
From that discussion thread, it looks like creating a group and then grouping on =Ceiling((RowNumber(Nothing)) / 20)
will give you what you want. You'll need to change the group properties to start a new page at each instance of the group.
As for "step by step," I'm not sure what you are hoping for: do you need help creating a report? Creating groups? Opening Visual Studio?