Grant Access rights to users based on who logged in (vb 2005)

hi,i have created a vb 2005 application that has a log in form where user put username and password to be able to log in.
In the back end i have created a sql database with the users table with username and password fields such that only users that exits in the DB will be able to log in.So far I have achieved this.

What I want to do now is grant access to different menu items depending on which user is currently logged in. I have added another field in the users table called usergroup which stores the group a particular user belongs to, the group assignement can be performed when creating the user from the application.
I need help how can i achieve this in vb(.net 2005)
looking forward to hear from u guys

godfrey