Before you can post in the forums, you must register. Begin by reading the Membership Instructions. After you have registered, follow these instructions:
Log in, using your username and password.
Select the forum you want to post in. You can first click on Home to see a complete list of the forums.
Within the forum, click on New Topic.
Enter your Subject. Be sure it tells other users what you're going to be writing about. If it's meaningless, they are not likely to click on it and read your topic!
Optionally, you can enter a short Description of your topic.
Enter your text, then click on Send.
Note that for a few days after you post your topic you will be able to edit it by clicking on Edit. So if you make a mistake, you can correct it.
Lastly, if you want people to read and reply to your topics, choose a title that will attract their interest. A title like "Just a Thought" won't get the attention of anyone that doesn't have both time to kill and a strong curiosity.