You are exactly right, a fish cannot turn into a lizard and then turn into an ape and then turn into a human, that idea is not evolution at all. You have a common misconception of evolution by means of natural selection. Creatures do not magically change from a fish to a lizard in their lifetime (magic), a horselike creature doesn't reach high and grow a long neck to become a giraffe (llamarckism). It is a process which occurs over the generations, and has to do with how sucessfull organisms are at reproducing and spreading their genetic material.
The principle is that between generations of organisms there are differences. You yourself are different than your parents, there is a transfer of genetic material between both parents and the permutation that results is you, in addition there are sometimes mutations in the genetic code which add furthur difference.
Now these differences are usually very minor, however sometimes a particular difference in an organism may offer an advantage to its survival and its relative reproductive success.
For example a lion may have a mutation which allowed for a greater degree of muscle strength which allowed it to move slightly faster. Now with this mutation which other lions dont have this animal would suceed at catching prey and would also have a greater opportunity to reproduce. When it has sex the same mutation which gave it stronger muscles could be passed down into its offspring giving them an advantage until the change becomes more and more prevalent in the population at large. Eventually all the lions in the pride (after enough generations) would have this mutation and they would all be stronger.
So you see the one fluke change in the DNA of the organism allows it a slight advantage in reproduction. That is the point of evolution, natural processes will favour certain traits depending on the biotic and abiotic conditions amd those traits may be passed to their offspring.
Over time, millions of years, these changes accumulate and new species may appear from these mutations.
The earth is older than 6000 years, The most obvious reason is that in the sky there are stars hundreds of thousands of light years away, there are galaxies and quasars even furthur away still. The radiation emitted by these things takes time to reach earth, they all travel at the speed of light (299 792 458 m / s) and can take longer than 6000 years to get here. The universe is at least billions of years old.
The solar system can be dated using the sun and tracing its point on a HR diagram, to work out its age which is around 5 billion years.
The planets, asteroids and comets in the solar system are loose particles left over from the formation of the Sun. Originally the gas and dust that would become the Sun was the core of a cloud much larger than the solar system, probably several light-years across. (One light-year is equal to approximately 6,000,000,000,000 miles.) The core was slowly rotating at first, but as it collapsed it spun faster, like a spinning ice-skater pulling in his arms. The rotation prevented the material at the core's equator from collapsing as fast as material at the poles, so the core became a spinning disc.
Gas and dust in the disc spiraled gradually in to the center, where it accumulated to form the Sun. But because dust is denser than gas, some of the dust settled to the mid-plane of the disc. These dust particles stuck together to make clumps, then clumps stuck together to make rocks, then rocks collided to make planets. In the case of the "gas giant" planets, Jupiter, Saturn, Uranus and Neptune, the rocky cores were massive enough to also attract some of the gas. The outer layers of these planets are made up of hydrogen and other gases.
So the Sun is the collapsed core of an interstellar gas cloud, and the planets, asteroids and comets are small lumps of dust or ice chunks which stayed in orbit instead of spiraling into the Sun. The planets all formed within a very short period, probably a few million years.
The earth itself is billions of years old, using radiometric dating one can determine the exact age of volcanic rocks and use these to construct the relative ages of rocks above and below them in the strata.
I shall post more when I have finished cooking dinner - please consider these things, an inquisitive mind is no threat to your beliefs.
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I suggest that you look over this site, it provides information in relation to the matter.
http://www.talkorigins.org/faqs/dating.html