If you Google UIView
you'll end up at the documentation - UIView Class Reference
Then you need to look down the list of methods until you find something that sounds like it will roughly fit your needs like these two:
- (void)insertSubview:(UIView *)view atIndex:(NSInteger)index
and
- (void)insertSubview:(UIView *)view belowSubview:(UIView *)siblingSubview
At this point you just have to read the descriptions of how the methods behave and pick whichever one is easiest to implement for your design. It's really good for your own learning if you try to find the answer yourself before you ask a question