Where to start
Three roads lead to the same editor: choose Custom food from the add button, tap Create food when a search comes up empty (the name you typed comes along), or scan a nutrition label and let it prefill everything.
The three steps
Info — pick an icon, name the food (that's the only required field here), and optionally add a brand and barcode. You can scan the barcode straight from the packaging — with it attached, future scans of the product find your food instantly.
Serving — define what "one serving" means: an amount in grams, ounces, milliliters, or a countable serving. Switching between weight units converts automatically, and the gram equivalent stays visible so there's no ambiguity about what you defined.
Nutrition — an editable nutrition label. Calories, protein, carbs, and fat are the core; beyond them you can fill in fiber, sugars, fats broken down, sodium, cholesterol, vitamins, and minerals. Pick the label layout that matches the package in your hand — US-style, non-US-style, or the app's own order — so you can copy values line by line without translating formats in your head.
Save it, log it
From the editor you can log the food immediately or add it to the plate; either way it's saved and lives in My Foods, searchable like anything else. Custom foods are private — nobody else sees them unless you explicitly contribute them to the catalog.