Ok for posting pictures lets see here. ill run through a test post then give you a quick guide on such.
First go to advance, then scroll down to manage attachments, This will open another browser, from here you will want to click add files on the top right. Then click select files which will open your computer to locate the pictures, You can do multiple files at the same time by clicking select files again. Then click upload. Once that is complete The box will close and u will see the pictures you have uploaded in the browser. Also at the bottom is a box that says attachments the picture you just uploaded from your computer should be there. There is also check mark boxes on the bottom right of each thumbnail. Put a check in the ones you want and click insert attachments. complete your post and submit reply.
Done this way yeilds the thumbnails as you see now. The first is one i took near coos, bay oregon of the sunrise, the 2nd is the lower narrows wayside just east of glide on the north umpqua river.
I hope this helps