First, to get to a forum, you open the group that hosts the forum. One way of doing this is clicking the group name on the Pamoya Groups page. In the top-right of the group page a list of group related links appears. Click the "Group forums" link to go to the forum.
Click "Post new forum topic" above the list of forum topics that appears.
On the page that appears, fill in the "Subject" and "Body" fields (they are required). You can optionally attach files to a new forum post. You can also add click-able links to your contribution. To do so, select the text that has to be turned into a link and click the second button from the left on the button bar above the "Body" field. Fill in the "Link URL" and the "Link title" fields and click "OK".
When finished, click "Preview" on the bottom of the page to have a preview of your contribution. When satisfied with the outcome, click "Save" to actually post your contribution on the forum.