I have a Nikon D60 and I'm having trouble with portraits and bringing everyone into focus?

I use a Nikon d60 for my photography and the majority of portraits that I do for people are group shots. I'm having trouble bringing everyone in the photo into focus, or at least making everyone sharp. Help please!

Added (1). I'm using a Nikkor 18-55 mm 1:3.5-5.6 lens

What lens are you using?

What lens aperture are you using?

Do you know that the sharpest aperture is two stops down from wide open?

Do know that the apparent depth of field is one third toward the camera and two thirds back from the focus point?

As you can see, this has NOTHING to do with the camera you use, but how you use it

Taking these things into consideration, you should get better shots.