Different #s of Parameters To Crystal!

Hello Friends,
I am new in programming, especially in Crystal Reports! From a web form, I am sending few parametrs to another web form where I will use them to create a crystal report.

I have the database connection, parametrs and evrything added for Crystal report to be generated, but an user can select only 1 choice and 1 parameter can be sent to the other form. Maybe all 3 choices or different combinations of 2 parameters!

How do I write or where do I put the logic for crystal report to expect different numbers of parameters?
I thought Crystal Report was simple, but it's making me crazy.


Right now, I have a report set up that requires all 3 parametrs.

I need to create reports, according to what user selects! With 1 , 2 or all 3 parameters. Also sorting by a certain parameter.
One more thing, I need to display the report in .PDF format in webform. (vb.net)

Please help. Thanks in advance.