If you want to issue a new identity for a participant, you can do it only from outside of your chaincode. Unfortunately there is no support for issuing identities inside your transaction or contract, which might make sense, hence this kind of a management is usually not part of the transnational logic. If you want to issue an identity from the outside world, what you have to do is the following:
1. Get your business network connection:
const BusinessNetworkConnection = require('composer-client').BusinessNetworkConnection;
2. Connect to your network, with a certain network card:
await businessNetworkConnection.connect('admin@mynetwork');
3. Issue new identity:
let result = await businessNetworkConnection.issueIdentity('Participans#email', 'name);
4. Close the connection:
await businessNetworkConnection.disconnect();
