At the current time you are not able to upload a picture directly from your computer so you will first need to obtain the image URL. You can either grab it from one of your listings or upload the image to a image hosting site like flickr, photobucket, etc. To grab an image URL on Google Chrome just right click the image and select "Copy Image URL"
In Mozilla you will select "Copy Link Location" and in Internet Explorer select "Properties" and it will pull up a box with the image link in it.
Next pull up the reply page in the forums and click the button to insert an image:
A box will pop up where you can paste the image URL. You can paste it by pressing 'Ctrl'+'V' or by
right clicking the text bar & clicking 'Paste'. After pasting the image URL you can click the 'Link' tab to send someone to the item when they click the image(make sure you paste the listing URL not the image URL).I hope that helps!! Feel free to contact me on Artfire if you have any questions/problems. Sorry about my lack of computer terms...as much as I learn about computers I will never know the language *<:o)
**EDIT** Adding a link to the image. You can also highlight your image (on the page you are writing your post) and then click the link button to add a link to the image.