First I would create this stored procedure within your instance and not within SSRS.

Then when you create the dataset, under Query type select stored procedure. Find your procedure name and click it. If it is not there then you do not have your data source configured correctly.

Once you find it and select it click the Refresh Fields button. This will automatically add all of the stored proc parameters to your report.

The answer on this MSDN question should help:

http://social.msdn.microsoft.com/Forums/sqlserver/en-US/f7b85430-66f3-4932-a69c-3e41ddee4f3a/how-to-pass-report-parameters-to-stored-procedure-in-report-builder-30?forum=sqlreportingservices