Note the SHARE icon at below-right of each image. It's a big rightward-facing arrow, between an icon of a star and that of a downward-pointing arrow.

Click that and you can choose how you wish to share. Copy the URL given if you want to embed, as I did here.

Flickr prefers this method, as you can click the image and visit the album it's from. (My example comes from an album of diners, for example.)

Besides this, another method I use for posting multiple images is to click the afore-mentioned "downward pointing arrow" icon. This one is for downloading the image, and it accesses various sizes of the image (if this feature is not turned off by the user). Click VIEW ALL SIZES. Simply choose the size you want to post, right-click for the image URL and post like any other image in a multiple-image posting.