Assuming you're talking about how to carry things while mountain biking, there are a few different ways.
One is to invest in a good backpack designed specifically for mountain biking. These backpacks will have features like extra padding and support, as well as compartments designed to hold water bottles, snacks, and other gear.
Another option is to use a handlebar bag or seat bag. These bags attach to your bike's frame and can be used to store smaller items like tools, tubes, and snacks.
Finally, you can also use panniers. Panniers are bags that hang off your bike's rack and are often used for longer rides or touring. They're a great option if you need to carry more gear with you, but they can make maneuvering your bike more difficult so they're not always the best choice for mountain biking.