I'm assuming you must be having trouble replying to a post as you've obviously found the New Thread button :-)
You click on the Reply button underneath the comment you wish to reply to - but some groups (such as the Reserve ones (Minsmere, Loch Garten etc) you will have to join first (a Join button top right). Then the Reply button will appear
Thank you, but i didnt realise a new thread was the same as a new post!! So i just start a new thread?! I admit i have found this 'page' very complicated. Theres too much stuff needing doing these days to have to figure things out. SORRY and THANK YOU,