If you want a link to another website to appear in your message you can just copy and paste the URL into your message.  For example, if I wanted to link to the main page of LongLocks, it would look like this

http://www.longlocks.com

If I want my link to look "pretty" with a different description (or the URL has lots of gobbledy gook in it that makes it really long), then I can use the tags.  I would start with the tag that indicates I am inserting a URL and inside the brackets tell it that the URL equals the long address.  I can then type in the description I want the link to have.  I then close the URL link with a bracket, slash and close bracket.  

Here is an example of what the link to LongLocks would like using this method.  (NOTE: I have placed a space after each bracket so that they are visiable).
[ url=http://www.longlocks.com] LongLocks HairSticks Boutique [ /url]

Removing the spaces, the link would look like this:
LongLocks HairSticks Boutique

Now you know how to enter links!  So link away to your favorite long locks sites!