To set up Neto your will need a Neto login.

Firstly Log into Neto normally at  https://www.<yoursite> 

In your Neto Control Panel, go to Settings & Tools > All Settings & Tools > API Settings 

Get the APIKey for the user you are logged into 

Fill in the information below

Store URl = https://www.<yoursite>

UserName you used to generate the key

ApiKey from above

Note the Advanced Setting for TaxCodes must also be set in the following way as Neto does not return this information. Add in the required tax codes.