To create a new thread, using Safari, go to Forums view and select one of the forums:
There, select "Post new thread":
Enter the title and write your post:
Then scroll down and post your thread:
Tap "create thread".
This is what it looks like on an iPhone. It's working similar on your iPad.
This forum is mostly discussing iPhones. We have a sister forum, which discusses iPads and everything related to it: Apple iPad Forum
Maybe you'd like to take a look at it.