To add your Bittrex API key to Bitsgap you will need to have an account on Bittrex where you can generate it from the back office.
Step 1: Login to your Bittrex account
Step 2: Proceed to API generation
When you are logged in, on top right of your screen you will find Settings, click on it.
You will be redirected to Settings menu where you need to select API Keys. Please note that you must have Two-Factor Authentication enabled on Bittrex exchange. Otherwise, it is not possible to generate API key.
Step 3: Create a new API key
On the API Keys page, if you have not done it before, click on the Add new key... link
Step 4: Configure your new API key
Activate all boxes as shown below (Read Info, Trade Limit, Trade Market) When you are finished, click the Save button.
Step 5: Receive your Bittrex API key
Once it's done you will see your API and Secret keys which you can link to your Bitsgap account. Be sure to record your API key and secret key somewhere safe.