How they feed astronauts on the ISS (International Space Station ?. For every 3 months are sent food, supplies (parts), water and new experiments in capsules unmanned Soyuz calls or Dragon.
The Dragon capsule can carry 2,400 kilos (2.4 tons). Manufactured by the company SpaceX is one of the first private licensed capsules attached to the ISS.
The much older Soyuz capsule, which have not changed since the 60 (or so), but now dock the Soyuz 19 (version 19 or TMA) but can carry up to 6 crew as they have capacity to be up to 2 days in space independently and can carry about 4100 kilos (4 tons).
First, the Dragon, is launched from a rocket Falcon 9, while the Soyuz, from a Soyuz U rocket is a missile modified nuclear weapons than anything else. It is making it very cheap, much more than the similar US.
The Soyuz U rocket is a standard 3 phases. If you want to know more about rocket stages: https://en.wikipedia.org/wiki/Multistage_rocket
This video will help you to understand how this rocket works:
And here is the docking procedure: