It took me several steps to post this one.
I haven't yet figured out how to do it. I only read forums from iPad and wait to post from laptop. This should be simpler.
To post from the iPad tap the HTML button and enter your text in the window that opens. It's an annoying way to have to do it, but if you really want to post from the iPad it will work.
That's how I did it last night. It works in a pinch, but otherwise I'll wait until I have access to my computer.