I would like to know please how can we get to the exoplanet Proxima b. I heard it is the potentially habitable exoplanet closet to Earth at only 4.2 light years away. So exciting!
It's habitability is uncertain. Red Dwarf stars that small could be unkind to their planets and strip them of most of their atmospheres. We'll get a better look at the exoplanets around Proxima Centauri when the James Webb Space Telescope is up and running. It's scheduled to launch in 2019 and it should be able to tell us something about exoplanet's atmospheres, which would go a long way towards estimating any habitability.
Actually getting there, even with a small unmanned craft is a long ways away. There's still significant technological difficulties with Breakthrough Starshot. The lasers aren't set up yet for one. For two, the aim has to be just about perfect, and three, we currently have no means of receiving a signal from a craft that far away. We have to improve our communications tech. Now, in theory, we know how to do it. We could build giant satellite dishes on the Moon, for example, or orbiting in space, but that's very expensive.
Another issue with starshot is that they have no means of slowing down, so they'd pass through the solar-systems they were sent to examine in a rapid fly-by, perhaps 10% of the speed of light, with only a few hours within the solar-system. Fly-by missions are still useful, and given the difficulty of transmitting data an orbiting mission in another solar-system might not make practical sense, because such a mission could easily gather more information than it could send back. The recent New Horizons / Pluto mission was a fly-by and it gathered a lot of information, that took over a year to send back to Earth.
Rapid fly-bys shouldn't be dismissed though. They can gather a lot of information that we have trouble seeing from Earth, even with newer and bigger telescopes.
More ambitious missions, and ships with their own fuel so they can break and remain in a distant solar-system are harder. That requires much more equipment, much more mass and as a result, would accelerate more slowly. Manned missions 4.2 light years away are so far out of reach that it makes little sense to talk about them outside of science fiction. A manned mission to Mars is hard enough and that's over 100,000 times closer.
Starshot is many years away. We might see Starshot launch in a decade or two - if it moves quickly. Then it'll be another 2 decades or so for the ship to reach the Proxima system and another 4 years and change for any information to be returned. 35-45 years is probably on the ambitious estimate before we receive the first starshot data.
Most of the new information about exoplanets that we're going to get over the next few years will come from telescopes like James Webb and others that follow.