I wonder if you photo bof's can help me?

I have a digital cannon exes 4 meg pixel.

When I try take a picture it looks terrible, light is all phased out, can't get good focus etc....

Should I be using the flash?

It has a macro mode but can't seem to get the colour and focus out of that either?

I even have a under water houseing, should i use that and if so what settings???

What settings should I be using? i.e. flash, exposure, manual ,automatic....

Anyone have the same camera that can give me some tips????