Hey b_a_w_2002, I use a website called 'Tiny Pic'. You upload pictures separately (which I find the only down-fall), and when it is uploaded you will see four boxes, and the words 'Picture uploaded'. One of the boxes says 'For message boards and forums'. All the content in just that box can be copied and pasted to show a big picture in your forum posts.
A good site to use for images is http://prnt.sc/
Another good thing is to use imgur (http://imgur.com/) then upload your images.
To get them onto the forums either get the embed link or use the tab up ^ and put the link in there: http://prntscr.com/82w427 is straight up link,
Or: http://prntscr.com/82w4p9 <--- NOTE this isn't working for me and probably not anyone at the moment I'm not 100% sure. I hope it gets fixed.
Putting in a straight up link should do for screenshots.
Thanks :)