Click any of the bottles that you have 2 or more of, and 2 of them will end up selected, offering you to mix them into one of the same kind but bigger level:

Well then there must be a bug in the system, because when I click on any with 3 for example, all 3 get selected.  Sometimes there is a pop up that asks if you want to mix two or three, and other times no ask and all 3 get mixed, which I understand means they are worthless when 3 mixed.

there doesn't seem to be an easy way to copy and paste from the game to this forum board.

No, you have to use external tools, like Lightshot (which has Chrome and Firefox plugins), Gyazo, or any other similar one.

Lightshot and Gyazo provide a way to upload directly. Or you can do so on Lightshot's site, or you can upload to other free services, like Imgur, TinyPic,...

All of them will provide you with a link when you upload, which you can just post here. Just make sure it starts with http:// or https:// (not wysywyg:// or something similar).