Your User ID is a unique ID for your account! With it, friends can add you, not to mention it is vital for your customer support inquiries. Here is how you can find it:
1. Look for the Menu button [≡] located at the top-right corner of the main screen.
2. Tap the [Settings] from the list.
3. Your User ID is located at the bottom-right corner.
4. You can tap the [Blue Button] next to your User ID to copy it.