Log into your account at, then select "API" here:
Click on "Create New Key".
If you intend to use the service for trading, then check all the "Write" boxes, except the last one, as in the screenshot below.
If you only need the service for infographics, all "Write" boxes should be unchecked.
Click on "Generate API key"; you can leave the field "Label Your API Key" empty or give the key a name like "3Commas" for convenience, especially if you have a lot of keys.
Now open the email account you used to register on Bitfinex, find an email with the subject something like: "Action required: Create API key - Nov 23 10:26 PM"; open it and click on "CREATE API KEY". If there is no email, wait 5-10 minutes and refresh the mailbox page
And now the API & Secret keys are in your hands:
If you need to delete the key for some reason, click on "My API Keys" on the same page, and then "Revoke":