1) Log into your account at https://bittrex.com
Note: You must have 2FA enabled on your bittrex account in order to create an API Key.
2) Click on 'Settings' on the top right of the screen.
3) Click on 'API Keys' on the left side bar under 'Site Settings'
4) Click 'Add new key...'
5) Enable 'Read Info', 'Trade Limit', and 'Trade Market'
6) Click 'Save'
7) Enter your 2FA Code and click 'Confirm'
8) Your API and Secret Key will appear in the table. Take note of your keys. The secret key will appear only once, so if you lose it you'll have to generate a new API Key
8) Enter your credentials on the right and click 'NEXT'