To get the spreadsheet. Do the "print screen" key on your keyboard, usually near scroll lock/pause break, paste the image to microsoft paint, edit and save.
To post. Do the post as usual, I generally use the FCKeditor, upload the picture to the gallery, and then link it in your post using the editor. Works great for me every time.
The FCK editor is ok, but tinyMCE is just buggy and bad. Its not worth trying to figure out how to make a spreadsheet work well with those options, so the picture thing works out great.