To post in an existing thread use the "write a reply" box at the bottom of the screen.
To start a new thread:
From the main menu select the forum you want to post in e.g type 2 forum". Select "..." On top right of screen and from the dialog box that appears select "new topic"
Thanks but thats my issue. Ive looked but i cant find the dialog box or the new topic link. It doesnt even say write reply at the bottom of other posts. Have deleted the app twice and re done it, but to no avail