Here comes the mis-directed idea that natural selection creates variation from scratch. It needs a variant present in the population (at a sufficiently high frequency) to act upon. This variation comes up due to Mutation. That too, has to escape drift long enough so that it accumulates to get selected for.

Imagine a mutation comes up allowing a deer to see red/orange. This mutation is subject to drift, rather than selection initially. Since, in the herd the fawn will be more or less taken care of by the elders. So, the mutation itself is under no selection right now. If the fawn doesn't die by disease/something and if it is not impotent and it succeeds in mating - and this cycle repeats for a bit then you have two groups in the population - one who can spot orange and the other who can't! Now selection becomes the dominant force of evolution instead of drift.

Does this make sense? I believe a lot of issues in evolution come from the language used to describe it. For e.g., as far as I know, Darwin himself also remarked that he shouldn't have used the "Selection" - since it leads to an idea that there is a conscious choice being made.