SO I did a bit more research to show you what the camera is doing in Manual mode in hopes that if there was any other confusion this may clear it up.
This as we have talked about before is how the light goes into the camera
Think of it like filling up a bucket of water from a faucet. If you open the valve wide, more water comes out and the bucket fills up faster. If you close the valve to a small opening, less water comes out and the bucket takes longer to fill. The same concept applies to the aperture/f-stop setting, but the key is that lower numbers equal more light exposure, which might confuse you at first. F/2.8 opens the aperture up to let a lot of light in, which is good in low light situations. F/16 only lets in a little light, and is good on bright days when there is a lot of natural light.
The ISO setting on your camera determines how sensitive your camera is to light. If you are shooting in a lot of light, use a lower ISO setting. Use a higher ISO setting if there is not a lot of light. 100 or 200 are the standard settings; set your ISO to 100 on a very bright day or 1600 in a low light situation. Keep in mind that a high ISO setting sometimes results in grainy or lower quality photos.
he shutter speed setting determines how fast the camera shutter opens and closes when taking a photo. Long shutter speeds open the shutter for more time, letting in more exposure and light.
If you are trying to freeze a moving subject, like a soccer player, set your shutter speed at 1/250th or higher. Of course, you can shoot slower if you want some blur for effect. Try shooting at 1/30th and move the camera with the player. Sometimes you can get a cool motion effect. Also, if you have a tripod, you can use a slower shutter speed. Bring the tripod to your kid's soccer game to get long exposure shots of the team playing. The background will remain in focus but the kids will be blurred. There are a few more kid's soccer game examples below.
Depth Of Field
For the ambitious photographers out there, I have one more Manual mode element to discuss: depth of field. The depth of field is usually not a setting on your camera, but you can control the depth of field using the aperture/f-stop setting. Many professional photographers pay close attention to the depth of field in their photos. A short depth of field isolates the subject in the foreground and blurs the background. You can achieve this effect with a wide f-stop setting, like F/2.8. If you want a deep depth of field, where both the foreground and background are in focus, try a narrow f-stop setting, like F/16.
As always, there is no "right" or "wrong;" it all just depends on what you are after. Use the settings above as your base, then adjust and shoot plenty of photos to see the different outcomes.
Hope this help!