Access DB Oracle and retrive role for users

Hi..i'm working with Oracle DB for the first time and i need to understand some
general concepts such as...

 First.

I'm working on an asp.net 2 web application where a user inserts username and
pws in a login mask, post the form, the application creates the appropriated
connection string and the user is logged in. Is this right?

Second.

i how can i retive the role for the user just logged in? I need it to denie him
the access to such directories like administrator or somethinge else...

thank you

Yes.  You will need for your application to add a reference to
System.Data.OracleClient and you will need the Oracle Client software installed
on any machine you are deploying to.  Check out ConnectionStrings.com to see how
to build an Oracle Connection string for OracleClient.

 As for roles in Oracle, review this information:
http://www.adp-gmbh.ch/ora/misc/users_roles_privs.html

thankyou very helpfull