Online business accounting

Hi Sir, we are starting a new website of www.textilebasket.com customer place a order to textilebasket.com then we are direct supply their order to our customer by courier company. so we are confuse how to prepare customer accounting. please give explain me as per below point 1. which a/c we raise for sales. 2. which documents we maintain for accounting purpose for sale. (like sale invoice, courier detail, payment proof) in above sale is it complusary maintain customer wise leadger.