By default Hoop.la uses "Graemlins," which are Social Strata's original name for auto-converted emoticons. (Long story short, it's named after one of our members who suggested the feature back in 1999.)
Now that emojis are a global phenomenon, you might want to incorporate some of the more standardized icons within your community. This tip will help you incorporate Emojis with (or instead of) your Graemlins.
First, choose which Emojis you want to use. Emojipedia is a good resource.
If you're going to add a lot of Emojis, it will be handy to create a document where you've pasted the Emojis and the corresponding keystrokes so that you can just go back and forth copy/pasting.
Go into your Hoop.la control panel, in Design > Graemlins, and click "Add Graemlin." Select "use emoji" and you'll see the option to paste emojis.
HINT: It will be easier for your members if you name the Emojis with keystrokes that are the same as common usage.
You can also add your own custom Graemlins, as described in this KB article.
Just for fun...here's a screenshot from some of the original Graemlin -related release notes, back when dinosaurs roamed the earth.