how to upload a blueprint to forum

When you write a message (like this one) you will see a bunch of smilies (old school terminology for emoticons) just under the text input window, to the right of the "Smilies" text you will see a paperclip icon. Click on it and you will see an upload button. Once uploaded you can click insert to add the images to the post you are creating (you'll need to upload an image too for blueprints).