How do you travel through time and space?

Sorry, I am only 13, so this may not be the best explanation

According to string theory I, there are 10 dimensions of supersymettry, only 4 of which are open to us, 6 are intertwined in another dimension (sorry, not sure which one), one is time, one is forward, one is sideways, one is up and down, and the fourth is through time

In the same way you measure metres, you can measure time, convert 1 second to one metre, and imagine life as a huge timeline

Now, if there is a device which could unlock the dimension of time, it would not be a machine, rather a portal, you would walk in, into a space where time is frozen, and simply walk backwards.

The flaws with this are the paradoxs it would create, but I am only 13, give me a break!

---

Not to lambast... string theory is indeed an interesting concept to behold, however the concept of multiple dimensions is complicated and infantile, and really does not hold any relevance to the question at hand. If anything, string theory serves only to complicate a simple question.

Now for the non-string speculations:

Traveling through space and time is a very familiar notion to you and I. Any time we move, we have traveled through space. By the time you've finished reading this sentence, you've traveled through time. All something has to do in order to travel through space-time is to have extensions in both space and time. Very simple.

However, if your question has been asked in the context of the science-fiction notion of time travel, then things get a little more complicated. In order to travel through time at a rate other than the rate that we experience time at, the simplest way to do so is to travel fast. According to Einstein's theory of relativity (which exists because classical mechanics becomes flawed when your frame of reference is moving), the faster an object moves, the faster that object experiences time relative to an outside observer. So, if QWOP, twin of THWOP, decided to leave her home planet on a space ship that traveled at 99.9% the speed of light on a voyage that would last twenty years for QWOP, her home planet, and THWOP, would have aged roughly 1000 years. This phenomenon is called time dilation, and can be observed in satellites above earth, who have to re-synch their clocks every now and then because their speeds dilate time.

Unfortunately for would-be time travelers, it is impossible to travel backwards through time. In order to travel backwards through time, one would need to exceed the speed of light, which is really quite impossible, or so we think. Some scientists think it possible to cheat nature however, with the use of wormholes. String theory can play a role at this point, depending on how you try to explain it. But don't hope for wormholes anytime soon.

Hope that helps.