I would say that either your computer is actually viewing pictures stored in your own browser temp files (on your computer) or the site where you are hosting the pics does not allow pictures to be accessed from a message board like this in order to protect their bandwidth. It can be confusing to be able to see the pictures yourself and nobody else can.
A valid URL for a picture, which the message board can recognize and retrieve, should end in .jpg, .gif etc. Yours does not which means even if they are properly stored on a hosting site which allows access, the URL is not correct.
A valid URL would look something like this
http://drdansinfo.com/DSC07655re650.jpg
Pasted into the message like this, the board simply creates a link. You can click on it to see the picture.
If I use the image tags around the same URL then the message board automatically retrieves it and it displays as shown below. this is moonlight on Mt Princeton.
Here is the same picture hosted on photo bucket. First the URL then using the img brackets.
http://img.photobucket.com/albums/v395/drdan/DSC07655re650.jpg
Try joining (free) and uploading a couple of pictures to
www.photobucket.com, getting the URL (which photobucket clearly identifies) and reposting some pictures here.