Hi Ajay,
1. If you are looking for ledger accounts, please click on "Accounting" which appears left panel of QuickBooks. You would be able to see all Ledger Accounts on "Chart of Accounts" screen.
2. To setup a customer, please go to the Sales tab >> Customers >> New Customer
To setup a supplier, please go to the Expenses tab >> Suppliers >> New
Please note that you will need to differentiate the name slightly in one of the boxes. For e.g if you name the customer Arvind you could add a full stop (.) to the name when you create the supplier, say Arvind.
A single entry for settlement can only be made through Journal Entry. This needs to be done through the + button >> Journal Entry. You would need to involve the Accounts Receivable and Accounts Payable accounts since a customer and a supplier are involved.
Hope this helps!