Lighting without the dark shadows

Hello All! I'm new to the forum and hope to get some help, as I'm also new to photography.

I have a photography light set of 3 lights. It has 2 umbrellas and also the little shade things that go over the lights (sorry for the terrible terminology, but I have no idea what they are called). Anyway, I have placed a basic white background up and am trying to take pics of my daughter. I love the look of plain white background and flooring. My problem is that I can't figure out how to prevent horrible shadows behind her. I understand that there will be some shadowing, but I don't want any shadows behind her...I want it to be a crip clear white background. Can anyone please help me out?

Thanks in advance.

Let me start by saying that I don't have a studio and I don't have studio lights. But when I get a shadow behind my subject and I'm using a flash (or a source of light), it is because the flash is not diffused enough or is not bounced (ie. pointing too directly at subject). Can you try moving the lights a little or turning them down (if that's possible)? Also, are you lighting the background as well?

First off, shooting with a white background is the most difficult background to shoot against. With that said, I'll just address your question about the shadows behind your suject. I'm not sure if you are just lighting your subject and not lighting the background or if you are lighting both your subject and the background which you are suppose to do. If you do not light the background, you will get shawdow on the background. You will have to play with the placement of your lights on your background and rearrange it accordingly. Also, if there is ambient light in the room that can case problems too. For my studio (which was my dining room, lol), I had to buy blackout shades for the windows as the windows in the room were creating shadows on my backdrop. There are several reasons why you are getting shadows and these are the two most common problems.

I do take pictures professinally but have a lot to learn myself I use a Canon 40D or XT or XTi and strobe lights.