Right click on the image, copy the location, and insert it into the box that pops up when you click the yellow box.
I highlight/copy/paste the thumbnail images on my site. Never tried it with Google images until now ...and it took a lot of deleting because it copied the whole page
I find none of it quick. I "save the image as" to my desk top then I save it to photobucket if I want it to show without having to click the image in a seperate box below the post.
You can also hit the PRINT SCREEN key then paste in your image software and crop the pic but you need a host to put the pic on the web
There are several ways to post pictures from google and here is one of them Once you found the image you want to post, click on it. Once the picture loads, right click on the "Full Image link" on the right of the image and select "Copy shortcut". You can now paste the iamge shortcut on the forum.
You can also upload pictures or "side load" pictures directly from the web. Click on "Manage Attachments" Then past the url(s) of the pictures you want to attach