Click the smilie button on the editor, and all the emoji's you want are there.
Smilies are not emoji's, so trying to paste text representations from one site to another will not work, ie :renderText: here. That is specific to a site to show a smilie image from usually a sprite image.
An emoji is a standalone visual text piece. It looks like a smilie to you, but it isn't written that way, thus can be copy pasted anywhere that supports emoji use.
Facebook, from memory, use emoji, as do most social networks.
These are emoji:
Get Emoji — All Emojis to
Copy and Paste
All of these are pretty much in the smilie dropdown here already, so unless we don't have it, there is no point copy pasting them. If I highlight a row from the above site, copy and paste it here, it looks like:
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Nothing difficult. Copy the smilie looking image (emoji textual render) and paste here. Looks like a smilie (image), but isn't, hence copy and paste, hence the vast availability of options.