I guess he wants to know about "how" he can achieve time travel, by what means. At least that’s how I understood. If that was the question you want to travel in the future or to the past?
www.bibliotecapleyades.net/ciencia/time_travel/esp_ciencia_timetravel25.htm
http://science.howstuffworks.com/science-vs-myth/everyday-myths/time-travel.htm
Read those stuffs. There are various ways to achieve time travel (all imaginary or in theoretically of course). Wormholes, black holes, cosmic strings are the things you need to know about.
If you would develope a machine for time travel, it should travel faster than light because the theory goes like this. If you could travel faster than light, time slows down. Wormholes and blackholes allows instance travels. Read more on the website and create some ideas. If you have more doubts, people here will be glad to help you out.