I think it's a matter of right clicking over the main chart, then click on "save as picture" and when the save as picture window pops up, click the "active chart(as is)", and then when the windows "Save as" window pops up, make sure "My pictures" is in the "File name:" block and click "Save" just to the right of it.
Then....on simplegreens site click on the drop down menu labeled "More tools" and then click "My Image Gallery" and when that page comes up, click "browse" and when you see the "Choose File to Upload" window pops up, click on the desired pic and then click "open" next to it and you should see your pic come up to the left where if you click on the "embed" block you should be able to copy and paste it to your post.
Hope that helps!