LERP(start, end, alpha)
There is a tutorial on LERP in the tutorials section. It's a fantastic place to learn many of the in's and out of C2. Especially to help new users to get there feet running and best of all. it's immediatly there adn doesn't require any waiting for a reply.
Start, this is the original start value of a number range.
End, this is the last value in the number range.
Alpha which is a 0.0 to 1.0 value. Represents the %0 to %100 of the two numbers. So here is a couple of examples.
50 = lerp(0, 100, 0.5)
440= lerp(200, 1000, 0.3) ie %30
However, often LERP is used for the fantastic use of acceleration to deceleration of movement over distance.
Player.Y = lerp(player.y, touch.y, 0.1)
This results that per tick the player will move 10% of the distance between the players current distance and the target distances. So the farther the player is away. the faster the players moves. However as the player get's closer the player will slow down do to the fact that %10 becomes smaller per tick.