Evolution

I am confused about all the information on evolution, creation and intelligent design. Hence I joined this forum to post this question.First to clarify evolution, I would like someone to tell me how evolution is explained in the following hypothetical scenario.There is a green frog population in an isolated island. All frogs are green in this population and they have been living fine in their green environment for ages.An alien species of plants invades their environment and the environment starts to change. Now, the frogs are no longer camouflaged in this environment. A bit of orange speckling on their green skin will, however, do the job of camouflaging wonderfully.But there is not a single orange speckled frog so far in this island population.Can someone explain to me how evolution will work to make the frogs survive?Will orange speckled frogs be the dominant variety of frogs in this island at a later time?Thanks in advance.

Thread copied to the Question on how Evolution works to produce new characteristics thread in the Biological Evolution forum, this copy of the thread has been closed.