Using a scope of work document
I strongly suggest the designer provide a build scope document or you can create one using a simple spreadsheet yourself.
You will need to know what is included in the build of your site, so you can go back later and make sure all of the functions are covered at the completion of the build.
If the designer says some of the extra functionality that you have asked for is out of scope, you can come to a new agreement over the build cost.
This prevents scope creep, so whether you stray from the documented plan and ask for changes or other things that were never written into the agreed-upon plan or included in the quote, it is all recorded in black and white.
The scope must be agreed upon and signed, changes and additions can come later.
I have included a sample spreadsheet with some pre-filed columns as a download under this video. You can add more requirements or delete some of the ones I have pre-populated.
In the spreadsheet, list all of the top menu pages you expect to have on your website.
List the functions that you would like to include in your site, from the notes you took when you investigated other sites earlier in the course.
Then in the next column of those pages, add what content and functionality you would like on those pages.
Send the scope document to the web developer, so you both have a clear list of expectations about the inclusions, delivery and price of the website build.