1: SPSite site = null;

   2: SPWeb web = null;

   3: site = new SPSite("http://server:100/sites/DevSite/");

   4: web = site.OpenWeb();

   5: SPRoleAssignment roleAssignment = new SPRoleAssignment("domain\\user","alias@domain.com","Nishand","Simple Test For You!");

   6: SPRoleDefinition roleDefinition = web.RoleDefinitions.GetByType(SPRoleType.Contributor);

   7: roleAssignment.RoleDefinitionBindings.Add(roleDefinition);

   8: web.RoleAssignments.Add(roleAssignment);