I think the problem you are having is shutter and iso settings. What mode did you take the pictures? Automatic, manual, Av, T, etc..
I suggest you do some light reading by googling photography just to get familiar with the common terms that will help you understand what makes what. Shutter, aperture, iso, Stops, white balance.
The idea is to have enough light for the camera to expose. if there isn't enough light the lens aperture should be open as much as possible. So the letter f. corresponds to that. The smaller the number the more light is allowed through the lens. If that hits the max then open up the shutter.
the slower the shutter the more light also gets into the camera. The trick here however is that if the shutter is open for too long any movement of the subject or you hand jitters will register as streaks. So here you want to find a balance. I usually try not to keep the shutter longer than 1/30-40th of a second when there might be movement. If you rest the camera on a tripod and decide to shoot stars at night opening a shutter for as l0ng as a few minutes will give you longer exposure and register even stars or clouds at night. But then you can't move the camera.
Next is ISO which corresponds to the artificial gain in a DSLR camera such as yours. yours goes i think from 100 asa to 1600. increasing the asa will let you shoot in darker situations but at a cost of grain.
Anyway read up a bit about all those terms and as you did shoot tests. shoot tests with different iso settings, and shutter speeds and upload to the computer for comparison.
All in all in the case of blurry pictures you have to set up the shutter to be faster than what you were using at the time. So if it was 1/15th of a second increase it to 30 or 40. if you can get it faster even better. open the aperture to it's fullest and see if that gives you enough light. if not than increase the iso number by an increment which goes up by double 100, 200, 400 etc..
The next thing you want to read is how to use the exposure meter built in the camera. If you look through the viewfinder you will see a digital line wth references going left and right. left means the subject you are pointing the camera at is reading a bit dark. it either is dark or maybe a dark sweater. the line going more right refers to overexposure. so look through the lens at various objects, walls, tables in your room and see how the line changes and the objects are light differently or are painted dark. google grescale and spot meter exposure to help you with that.
Lastly read in the manual or google(even better) how the automatic, AV, TV, M, etc.. vary in function. I suggest learning what av and tv do and shoot with that as they are semi automatic modes. They allow you to have control over say the shutter but the camera automatically compensates the apeture and vice versa. As you get comfortable with that shoot more in manual.
Lastly the DPI is camera resolution is the important spec of that camera. a 12 mega pixel camera isn't much better or useful from a 6mega pixel. That's just an advertising ploy in most cases. Unless you are blowing up the photos on a larger canvas the difference isn't noticed. the quality comes from the pictures aesthetic, and printing quality. in most cases wal mart will give you. since memory cards are large enough these days i would should either large jpegs or raw.
also download or buy aperture or adobe light room to see how you can further manipulate the photos in the computer with white balance, colours, brightness, contrast, etc..
the canon you have is a great camera. enjoy it and the best part is that you will be learning something new a long time while getting better and better with each day.
i can't believe or ranted for so long. i apologize for any mispelling and grammar. This was a rushed write up but i hope it helps with your start.
