Once logged in to Zapier, look for the "Make a New Zap" button:

Next, you'll need to choose Trigger (from) and Action (to) apps. Start with Twitter as a Trigger app:

Then choose "Search Mention" as the trigger:

Next, choose Adafruit IO and "Send Value to Feed" for the action. (If you don't see Adafruit IO listed, remember that you have to use this invite to access the app.)

Now you should be able to hit continue. You'll be prompted to connect a Twitter account (you've already made one of those and logged into it, right?):

You can give it a meaningful name. You'll probably also want to switch "Auto Follow" to "no", unless you really want to follow Zapier on Twitter. Click "Continue", and you'll be sent over to Twitter to authorize Zapier to talk to your account:

Once you click the "Authorize app" button, you should see something like the following:

Once you hit "Continue", you'll be prompted to an Adafruit IO account. This one take a bit more work, since you'll have to find your AIO Key and copy it over.

You can find your key by visiting the Adafruit IO settings page and clicking "View AIO Keys":

Copy this key, and paste it into the "AIO Key" field on Zapier, then hit "Continue".

Next, specify a search term to trigger on. I'll use "adafruit io":

Next, pick a value from Twitter to post to IO - I went with the text of the tweet:

Then pick an IO feed to post to:

Before you get any further, head over to Adafruit IO and make sure you have a matching feed. I did this by clicking "Your Feeds", then the blue "Create Feed" button:

Now you can click "Continue" on Zapier and test your new Zap:

If you look at the feed on AIO, you should now see some sample data:

Assuming everything works, give it a name and turn it on:

I initially searched for just the string "adafruit" and quickly used up the 100 tasks allotted to a free account. A "task" is, more or less, any time Zapier takes an action (like posting a bit of data) on your behalf.

Here's my Adafruit IO twitter mentions feed. I also created a dashboard that displays the most recent tweet. (For more info on dashboards, see Adafruit IO Basics: Dashboards.)