My advice is to stop shooting in Manual mode for now. Go back to it when you know why you need it and how to do it correctly. Until then, it's going to get you poorly exposed or poorly focused shots.
Personally, I'm going to work in RAW, but I'm willing to use software to edit my shots. (Canon's Digital Photo Professional came with your camera and can do this at a basic level.) If you're not willing to edit, or in certain other cases even when you will edit, you may prefer to work in JPG, because you can work faster in burst mode, for example.
Learn to shoot in Av (aperture priority) or Tv mode (shutter priority) for now. How do you decide which to use? Think about your priority for the shot.
Is the subject moving? Is the light very low or very high? Am I using a big zoom lens, without IS (Image Stabilization) and handholding? I'd generally pick Tv first. My shutter speed is my top priority. I will set the shutter speed and the camera picks the aperture to give a balanced exposure on neutral-toned subjects (grass, but not snow, nor something very dark).
Maybe I want to freeze motion. In Tv, I want a fast shutter speed, maybe 1/250 (the viewfinder will say "250") for a slow moving subject (a flower in a 5-10mph breeze) I want to freeze. I might want a very fast shutter speed like 1/2000 for a fast moving subject like a racing motorbike. I have to have enough light to get this, and I may need to set ISO higher to do so. (If the aperture number is low, like 2.8, or 5.6, and is blinking in the viewfinder, I don't have enough light to achieve my set shutter speed.) One of the best parts of digital is you can change ISO to fix this issue without replacing the film "halfway through the roll". Set ISO higher and try again. (On the other hand, if the aperture number is high and blinking, I have too much light and need a lower ISO or an ND filter on the lens.) Am I on my shutter speed without the aperture blinking, and my subject is focused? I take the shot. I look at the display to see if the shot came out. I want the histogram showing on the display, and a balanced graph for neutral subjects. That tells me I'm close enough on the exposure to edit it and have it come out right.
Or, I may want a slow shutter speed, for a particular effect like having water in a waterfall appear silky. I'm still going to use Tv mode. I probably need my camera on a tripod for this, depending on my lens' focal length, but I might set a shutter speed of 1/15. A lens without IS and handheld is likely to give a blurry shot with such a low shutter speed.
I'll use Av when shutter speed isn't critical (stationary subject, average light level) but the depth-of-field-- how much of the image will appear in focus is important. Then my aperture is my priority; I set that, and the camera picks a shutter speed to give a good exposure on a neutral toned subject for that aperture. I might want a low aperture, like 2.8 or so, though each lens can only open up so wide (small aperture number) at a certain focal length. You can't set a wider aperture than the lens allows, no matter how you set anything else. With f/2.8 or larger (smaller f-number) aperture, if your lens allows it, the depth-of-field is very narrow, which does a great job of softening distracting background detail. Some lenses don't give their sharpest images though at extreme aperture settings, so if I'm going to enlarge a lot, I may want f/8 or f/11 if the depth-of-field isn't critical and shutter speed isn't critical. Or I may want the greatest depth-of-field I can get. Then I may need a tiny aperture (large f/ number) and again, a tripod, an Image Stabilized lens, or a high ISO so I can handhold my camera and still freeze the subject, because with the tiny aperture, I'll have to have a slow shutter speed.
Learn the triangle of correct exposure: the three factors which interact: ISO, aperture, shutter speed, and how they affect other aspects of a good shot such as focus and DOF. Later you can work on compensating exposure for subjects that are much brighter or darker than neutral, like snow or something nearly black. For those subjects, the meter often does not give a reading that will get you a good exposure even after editing, so you have to compensate. That's another long post or some time reading Understanding Exposure.