Several views are available depending on which kind of tasks you want to do:
Start by filling the fields in the template called "######## - Customer" such as your logo, address etc. Then you will be able to create a new quotation/invoice for any customer quite easily by clicking on the arrow near "New" on the top right side of the table.
In order to generate a quotation or invoice, modify as you wish the fields available (or add some) and simply export the page related to the line as a PDF. Fields are numbered for the PDF to be generated using an order you choose.
Here is an example of a customer that needs to be modified.
Also add you as a customer so that you can assign tasks to you in the Tasks database.