Welcome to the ATF, Cownseling!
The images have to be hosted on another site; I'm not sure if this works with Instagram, but on Photobucket, Flickr, DeviantArt, etc. all you have to do is right click on the image, select "copy image address", and paste that URL in your post on this site. Wrap it in image tags [ img ] http:// www. yourimage. jpg [ /img ] (without the spaces) and you're done!