Do you have experience in html/xhtml or CSS? Without knowing some of the basics you're going to have some problems.
A site worth using to learn both languages is W3C Schools. Google it cause im too lazy to go get the website atm

Its an invaluable website I even use when I forget something.
If you want some easy time coding, you can use Dreamweaver from Adobe, however it costs a pretty penny so up to you how you get your copy

Other than that you could use Publisher(?) I think thats what its called. I believe its a program provided in the Microsoft Office package or another. I can't remember. Outside of those just use notepad and use tutorials to learn how to code.
A standard 7-page website is all static so you shouldn't have to worry about PHP. But if your Aunt wants them to be able to purchase directly off the website then you need to learn how to make a database (MySQL or Oracle will work) and PHP/maybe Javascript.
Coding is pretty simple. Its not as complex as say as making a video game. Most of your designing is done within an image editor like Photoshop. If you're proeffficient in Photoshop/GIMP/other image software, you got a step up on everyone else. When you get into coding the pages themselves, its mostly copy and paste because 6 of your 7 static webpages are all nearly the same with the text content the only thing varying from the first page. So literally you're copt and pasting your code 6 more times after the inital first page is made.