You click on the tickers in others signatures. It will ask you for your own information, and instruct you on how to make your own tickers.
After they're made, codes are generated for each one. Then you go into your control panel (CP) and edit your signature. You copy paste the code you need into the box. Preview beforehand to make sure you have the right code, as there are a few to choose.
You can still participate no matter what part of your pregnancy journey you are in. This forum is so big, unless someone really made friends as part of a journal they started or joined..it isnt' all that common.
Most times, I only recognize the names from trimester to trimester.
I usually add my .02 to other people's threads I find interesting, however i do start alot of threads, as i'm very curious, or want to know what others think, or if something happened to them too.