multiple select in the parameter field in Crystal reports 8.5

I have a multiple select in the parameter field in Crystal reports 8.5 how do i check against that value in my SP?

Suppose I select 2 user from Drop down say

Mary
John

Are they comma seperated the way they r in Web based apps?
how do i build a SQL String based on the User criteria?Where is the dropdown - in Crystal (as a defined range of inputs) or in an application devloped from Vb or C++ or similar?
To use the VB example, when you populate a combo box, you can assign a value to the .ItemData property of the combo, and then return that to the report via the .ParameterFields collection exposed via the CR Active X control.
Say you populate your combo with data from a table:
RecordID Name
1 Fred
2 Mary
3 Joan
4 John
etc

then in VB code would be
...open recordset
...start looping thru records
cboTest.AddItem value_to_appear ' eg Fred
cboTest.ItemData(cboTest.NewIndex) = id 'eg 1
next

when you click on the combo, you can get the index and pass it to crystal
lngID = cboTest.ItemData(cboTest.ListIndex)

then in your code you can pass that to report when you open it, eg
Dim objPrintApp As CRAXDRT.Application
Dim objReport As CRAXDRT.Report
Dim objParamDefs As CRAXDRT.ParameterFieldDefinitions
Dim objParamDef As CRAXDRT.ParameterFieldDefinition

' code presumes you have an input parameter to your report named pID
' Set the report source
Set objPrintApp = New CRAXDRT.Application
Set objReport = objPrintApp.OpenReport(strReportSourcePath & strSource)
objPrintApp.LogOnServerEx put logon parameters here

Set objParamDefs = objReport.ParameterFields
For Each objParamDef In objParamDefs
With objParamDef
Select Case .ParameterFieldName
'It finds and sets the appropriate Crystal parameters.
Case "pID"
.SetCurrentValue lngID

' add other Case conditions here to handle other parameter names.

' Catch-all for others
Case Else
strInput = InputBox("Enter a value for '" & .ParameterFieldName & "'")
If strInput <> "" Then
.SetCurrentValue strInput
Else
Exit Sub
End If
End Select
End With
Next

objReport.PrintOut

hope this helps

dave|||Thks for ur prompt reply...but the drop down is in crystal reports 8.5

I am using Crystal reports 8.5 stand alone with enterprise server......i mean i not using VB or anything else as App dev.
I have SP in SQL server 2000

I need to select multiple values from the drop down of the parameter field.
how do I put those values in the drop down of the parameter field which needs to be passed to the SP?

How do I build the Sql query once the multiple values r selected? are the multiple values comma seperated??