I am sure House will be along to exlplain or point you in the right direction. There is a chance you are not able to with a low post count , but when able i do this. Open another window with Silver stackers and use the upload image button. When the next screen shows it will tell you to select image. Select your image and then submit button. When it has loaded there will be 2 different options , copy the one you want and paste in the other SS . It is dead easy (the second time you do it) and failing my wishwash example quote someones post with and image and look at what the image looks like in plain text.
Ha! Check here- http://forums.silverstackers.com/message-59503.html#p59503 If the above suggestions don't work, upload to imgur.com/upload and post the BBcode
What sterling-nz said. I had the same problem just a few days ago and spent probably two hours trying to figure it out. It's not the most user friendly system but once you've done it the first time you'll see it's not overly complicated,. Just a little fiddly. Good luck!
Try using the Search Button rather than keep asking questions around. This Forum is well establish already, information are there for a look up... Have a nice day http://forums.silverstackers.com/search.php