Digital camera

hi i just got a digital camera at first i had problems because the pictures were grainy but i seem to have fixed this with changing the iso to 100
but now the pics seem to b blurry it kind of looks out of focus, if i take a still moving object outside it is better but still a little bit blurred although not much, but inside it is worse and if i try taking a pic of my kids well there is no chance it goes far too blurry because they wont stand still enough, also the flash seems to affect it if i take change the flash to other settings i am not sure how to explain this but there is about 5 settings for the flash including on and off and one that puts the flash on but seems to make a dark pic, this setting seems to make it not blurry but it is too dark even though it flashes??
dont know if u can help but would be greatly appreciated if u could. thanks