iphone sdk tabbased application?

i have two questions:

1>can anyone suggest me a good tutorial for:

ViewTransitions (transitions between 2 views) - all variations (curl, flip etc)

2> i am making a tabbased application where i have navigation in each tab, i hide it but n开发者_开发问答ow i have to put a png of back button where previously navbar was present .. how can i put that custom png and how to redirect it to previous page...

thanks in advance...

UIButton *btn_back_en=[[UIButton alloc] initWithFrame:CGRectMake(168,20, 257.134, 54.512)];
[btn_back_en  setImage:[UIImage imageNamed:@"Back.png"] forState:UIControlStateNormal];
[self.view addSubview:btn_back_en];
[btn_back_en release];
[btn_back_en addTarget:self action:@selector(viewlo) forControlEvents:UIControlEventTouchUpInside];


-(void)viewlo
{
info *viewController = [[info alloc] init];
[self.navigationController pushViewController:viewController animated:YES];
[viewController release];
}