We have a new member who is struggling with posting from his phone. He is using the CF app, but hasn't been able to post from it, only reply to private messages.
From the forum he wants to post to there is a little box in the upper right corner of the screen. Tap that button (box with a curved arrow in it) and then choose to reply to thread. Alternatively he may tap the little blue checkmark above any post and select to quote that post and then the input window will also appear.