Cmh, you may as well make a new suggestion in the middle of an existing topic - everyone else does! Actually the only problem (for you) is that I might overlook it. But I have made a note of the lamper suggestion, and I'll answer it in due course.
But starting a new topic is not too hard. I'll try to explain, assuming you know very little about using the forum. You need to be on the page that shows the list of existing topics in whatever category you want to post in. The forum has 6 categories. This one is "Words". On the page you have open you'll see a line towards the top like this:
Lexigame Community > General Category > Words > three suggestions
If you click on "Words", you will get to the list of topics for the Words category (including this one, "three suggestions"). At the top of the list, towards the right, you should see
MARK READ | NOTIFY | NEW TOPIC | POST NEW POLL
Click on "NEW TOPIC" and you'll create a new topic. The main difference from replying to an existing topic is that you have to supply a "Subject", i.e. a heading for the topic.
If you don't want to start a topic in Words, but in another category, you can click on "General Category" and you will see all 6 categories, so you can select the one you want.
If you're still unsure what to do, you could try the big yellow "Help" button at the top right of every page. This opens up a set of Help pages that go into a fair bit of detail, with graphics.
Good luck!