The type of information we know about exoplanets today: Mass, Radius and distance from the host star [click to enlarge]. Plot generated on the http://exoplanets.org/plots site – try plotting your own graph!
Twinkle, as you possibly know by now from reading our website, is not a mission trying to find new exoplanets, but rather to study known ones. This means of course that to do our work, we need the exoplanets to already have been discovered.
There are many ways to find a planet, some unexpectedly simple for such a complex field as astronomy, and some slightly more abstract.