Looking Up Recipes and Uses
What the item list does
JEI draws a list of every item in your game down the right-hand side of any open inventory or machine screen. The list is the starting point for everything else: you find an item there, or point at one you already have, and then ask JEI either how it is made or what it is for.
Those two questions are the whole mod. Show Recipe answers "how do I make this?" and opens the crafting grid, furnace recipe, or machine recipe that produces it. Show Uses answers "what can I do with this?" and lists every recipe the item goes into. Both work on an item in the list, an item in your inventory, and an item already shown inside a recipe, so you can walk a chain backwards or forwards without closing anything.
Moving around the recipe screen
One item often has several recipes, and several different kinds of recipe. JEI groups them into categories, one tab per category, and pages them inside each category. Four actions move you through that structure:
Previous RecipeandNext Recipestep through the recipes one at a time.Previous Recipe PageandNext Recipe Pagejump a page at a time when a category holds many.Previous Recipe CategoryandNext Recipe Categoryswitch between the tabs, for example from a crafting table recipe to a furnace one.Close Recipes GUIbacks out and returns you to the screen you came from.
When a recipe accepts several alternatives in one slot, JEI cycles through them in place. Pause Recipe Ingredient Cycling freezes that animation so you can read the slot you care about.
Two more actions worth knowing
Copy Recipe ID to Clipboard puts the recipe's internal identifier on your clipboard, which is what a mod author or pack maker will ask for when you report that a recipe looks wrong. Share Item to Chat posts the item you are hovering over into chat, so other players on the server can hover it and see exactly what you mean.
Where the keys live
JEI does not put all of its controls in one block. Open Options, then Controls, and look for the category headings that begin with JEI: JEI (Recipes) holds the recipe actions above, JEI (Hovering With Mouse) holds the ones that act on whatever is under the cursor, and the rest sit under JEI (Search Filter), JEI (Overlays), JEI (Cheat Mode) and JEI (Edit Mode). Show Recipe and Show Uses each have two slots, so you can keep a keyboard key and a second binding for the same action.