Windows in their infinite wisdom didnt include one when it went from XP to W7. I googled for something similar(i think its actually this one as it exactly the same) and installed it. Been using it daily since and thats got to be 4 years or so
You would save the pic you like to your computers pics, then opposite click on it(im a lefty so always confused about which righties use ) The drop down menu gives the sizes s,m,l or custom which for most and here i set for 999x999
It then copies it to give you another sized as specified, that you load into here and thats it.
ho do you get smaller images in the thread which click to a larger image in the hosting site. Ive seen a few people do this in the for sale threads. i helps not having massive pictures posted in the thread?