LOL Breny - I LOVE it that you couldn't wait
!
Great piccies already!
"A" mode is fabulous - that's what I shoot in almost all the time - this is "Aperture Priority Mode" - and *you* can choose the aperture, the camera then chooses the approp. shutter speed for you. You want a wide aperture/f-stop (ie. 1.8-4 ish) to blur the background. Your lens may not open to 1.8, all lenses are different.
It's also diff. w/ zooms...w/ zooms like you're using, it's not as easy to just choose an aperture/f-stop. That's the reason people love "Prime" lenses like 50mm I've mentioned - there is no zoom, but you can have total control over the aperture, which is super fun.
Now, whatcha need next is the add-on flash SB400 - so you can "bounce" the flash rather than have the flash hit directly at your kiddos.
Welcome to your new addiction!