Create User Groups and Roles in SharePoint Object model

Adding the Group

using (SPSite site = new SPSite(“http://yourdevbox:1337″))
{
   using (SPWeb web = site.OpenWeb())
   {
      SPUserCollection users = Web.AllUsers;
      SPUser owner = users[string.Format("{0}\\{1}", "Domain", "Owner Username")];
      SPMember member = users[string.Format("{0}\\{1}", "Domain", "Member Username")];
      SPGroupCollection groups = Web.SiteGroups;
   }
}

string GroupName = “Super Exclusive”;

string GroupDescription = “Super exclusive group description.”;

groups.Add(GroupName, owner, member, GroupDescription);

SPGroup NewSPGroup = groups[GroupName];

Adding the Role

SPRoleDefinition role = Web.RoleDefinitions["Full Control"];
SPRoleAssignment roleAssignment = new SPRoleAssignment(NewSPGroup);
roleAssignment.RoleDefinitionBindings.Add(role);
Web.RoleAssignments.Add(roleAssignment);
Web.Update();