How to lock certain fields in a form?

I use adobe forms for my contracts in a roofing business. I need my sales staff to be able to fill in the prices for several options and lock those fields before sending to customer. I will then need the customer to be able to select contract choices, color selection and sign. The only option I'm tech savvy enough to know is to make the price fields "read only" after filling them in. My staff aren't quite advanced enough to do that every time. I'm sure there's a more efficient method. **I have no idea how to create a javascript code, button or bookmark**