You don't need to
believe, there is strong evidence to support it.
These include:
1. Fossils (including their distribution in time)
2. Similarities between species - both chemical and anatomical (e.g. you mentioned the thing about DNA)
3. Artificial selection/selective breeding.
This site sums it up very quickly and simply.
Most breeds of dogs we know today have been created by selective breeding in the last two hundred years. Therefore, it is absurd to think given millions of years that a similar diversity cannot occur naturally.
Also, on the note of the eye, it is a flawed design. The position of the optical nerve means we have a
large blind spot at the rear of our retina. If a creator did exist he dun goofed.