sql server report service parameters

Question

I want to add report parameters to a sql server report service 2008 that has been generated by the report wizard and have the parameters work.
I can get  the report parametes to look like they work by doing the following:
 1. select view then report data then right click parameters in the report data window.
 2. I then select add parameters then enter a 'name' then enter a prompt name and then select data type.
 3. I then right click on the dataset and then click dataset properties and then click on parameteres in the dataset properties window and add
the parameters I want.
 The above looks ok, but the parameters do not work.
 What do I need to do get the report parameters to work either after a new report has been setup using the report wizard and/or adding the
report parameters to work at a later time.