what you mean by design work. You are bad in producing graphical work or you are just looking for html editor. You can use frontpage as html editor. I recommend you buy templates from templatemonistor.com. they have pretty neat templates for almost all kind of web sites.
When you get to the site (it will all be on a local computer, not web accessible[not that it matters]), it will need a login form (but I want it to look nice). Then once logged in, you can click on a left menu which will have.... Clients, Employees, Create Invoice, Create Estimate, Reports, but when you click Employees and Clients, it should drop down to View, and Add.
Then I will need to create an HTML form that looks like an invoice and estimate and then convert to PDF to download and view.