Could you please be more specific about your request? Do you mean to configure an IAX account in Zoiper for Android?
If so, you would need to have the account details from a provider, then to run Zoiper and to go to Configuration from where you should open the Accounts section. Select "Add account" and answer on the pop-up questions.
In case you are going to add account manually you would need to choose the account type - SIP or IAX and then fill the details like domain, username and password.