I have a Canon 600D and in manual mode, if I make the shutter speed higher, then the screen turns blackish/black; but with the same settings when I open the camera's flash it works well. In the day, the flash looks bad--that's why I can't shoot at daytime in public.
Quite simply the faster your shutter, the less light you get to the sensor.
You have 3 options:
- lower your shutter speed
- widen your aperture
- increase sensor sensitivity (ISO)
The point of manual mode is to give you COMPLETE control, but it sounds like you dont yet understand the way exposure works.
I would suggest you use P (basically full auto aperture/shutter) until you have learned a bit more