Wholesale Gorilla uses customer tags to discount products for customers who are logged in to your shop. You can create tags manually from your Shopify admin, or tags can be created automatically when a new customer signs up for an account (see Customers section in the user guide).
You can create any number of discount rules that apply to your entire store, a specific collection, product, or product variant. Once a tagged customer is logged in, anywhere a price is displayed on your site will be updated to the price specific to that customer.
That's the basic run-down of how things work. You can keep it as simple as that or dive deep to create a dynamic and fully customized wholesale experience for your store.