Help with online shop please

I need help please.  I've managed to add products to a shop in pages, but I am wanting a drop-down under a 'Shop' heading to list all of my products in categories, but all of the stuff I've been reading has just confused me.  I'm new to this and have no idea.  Thank you in advance!

You'll need to add a folder to the pages menu, and add links to the folder, those links can be categories, use this guide to set them up:

https://support.squarespace.com/hc/en-us/articles/115015977088

Hi, I have added a store (collection), I have added some products and categorized them.  Step 2 is 

Click the + icon next to the section where you want to add the link. 

If I click Pages, where is the '+' icon??

The plus (+) icon is on the right, highlighted yellow:

You want the one next to MAIN NAVIGATION. Then click and drag the link into the folder.