How far can I get this thing to reach,and how ?
With a good antenna, and the antenna tuned for best SWR, about 8 miles from mobile to mobile, and about 12 miles from mobile to base radio.
You can modify the radio and turn up the power, it will get you more range, and make the radio sound louder, but you will still be limited, because radio is line of sight. Hills and structures block RF signals. you go down a hill, you will loose distance.
With a cobra 29 that has been tuned up sitting on a hill about 1400 feet above sea level, I was able to talk to some one on a base radio about 50 miles away with out my amp on. I also have a very very good antenna. not something you normally see either.
With a clear on blocked line from antenna to antenna, you can talk really far on a stock radio. There is a saying for CB antenna's. "Height is might."
There are a lot of things that effect the distance a CB can reach.
If there is Skip active, you can possibly talk thousands of miles with a stock radio. Skip is when the ionosphere becomes charged by solar energy form a solar flair and causes the radio waves to bounce off them, making it seem like you have a straight line of sight to places that would normally be blocked by the natural curvature of the earth.
Then there are Linear amplifiers. They increase the power of the signal of the radio. They will increase the output range, but then you may be talking to people that don't have an amp, and that you will not be able to hear them because they do not have enough power to reach you.
So, get a really good antenna. Make sure it is tuned for the lowest possible SWR. Refer to the manual that came with your radio on how to find out your SWR, and how to lower it. There will also be instructions on how to tune the antenna that came with the antenna. Then bring the radio to a CB shop or a CB tech and have them tune it up. It will cost about $30.
With my radio barefoot, and can normally talk around 30 miles or more without worrying about hills and obstructions. (Barefoot means, without the amp on)