Sorry, I can't figure out how to do this, only full image (that is too big), or posting a url link.

Is there a way to post a thumbnail of the pick, and you click the pick and it takes you to full size image? I see others do this, but I'm not sure how to do it.

@JonW - Use advanced reply (hit reply on far right side), then attach file using attach function on right side, then once it's uploaded click the "insert" link right beside the uploaded file name, and use "Auto" not FullSize
Fernando made a guide about this - [Guide] How to insert pictures or attach files to a post