Need help with UI!

Hello!! I’ve developed an audio plug-in in xcode 3.2.6, and I’d like to create a custom UI. I’ve been looking for information on this web about how to do it, but I feel completely helpless. I don’t know how to start.
PLEASE, could you tell me what should I do, step by step?? Please… I’m quite despair.
Thank you!

Does this help?

Thank you! It is helpful. But I really need to know more, the whole process from the beginning. Like, shall I open xcode? shall I add a new class? what shall I do?