I don't know what you mean about having HTML enabled, but you haven't given us anything to look at so we can even guess at what your talking about. Give us a URL and we may be able to see your problem.
Now I see what you asking. Putting a image or clickable link in your forum is the same as putting it in a web page. For the image you use a tag. Using your example, a tag might look like the following:
This forum has HTML enabled, but in the above example, I have forcibly disabled the HTML from actually working. You would just type it in as you see it.
A link looks a little bit different. Again, using your examples, a clickable Link to Bravenet could be created in your forum by simply entering the following code. Note that the code below is used in the previous sentance, verbatum.
Again, I have disabled the above code, so that it is visable to you. To insert code so that it is visable to the viewer, replace all instances of the < character with <. This prevents the code from being interpreted, but displays correctly for the viewer.