To post a link, type your message in the normal manner.  When you're finished, highlight the word or words you want to represent the link.  Then, click the Insert/Edit Link button above the composition box and enter the URL of the webpage you want the reader to see.  Click OK, and the highlighted word will become the link.  It will be a different color, so the reader will know it's a link and will look like this....

To see the RV America website, go HERE.