SAP .Net Connector 2.0: Logon Information

Im using VB .Net 2003 and SAP .Net Connector 2.0.

Im able to connect to SAP and displaying data on datagrid. Now, im creating my own logon screen where user key-in their client no, user, password.

My problem is how to validate the user. How to check whether the user, client and password being entered correctly?

Thank you.

regards.