Two ways:
Go to the reply page first where you typed that message.
If you have an online photo account at a hosting site like Photobucket, you can link directly to it by copying the URL (website address - you know,
http://www etc), then clicking the image button above the smilies (2nd one on the second row), then pasting the URL in between the two [img] boxes. That will link directly to that photo and the photo will appear in messages as long as the image remains at that site. You can also use this method to link to a photo on another page if you want to use it as an example of what you're talking about.
The other way is to upload it directly from your computer. To do that, click the "Additional Options" below the space where you type your message. The last thing is an option to Attach with a Browse button. Simply use that to go to the folder on your computer where the image is kept, just as you would with and e-mail message and then post your message. Two disadvantages with this method is that you are limited in the number of photos per post and after awhile, the server gets full and Ross (69ChargerRT), the Administrator, deletes the older photos. That's why, when you look at some of the early posts in some of the older threads, you'll find broken photo links.
