<p>Dial the exposure down it's horribly overexposed.<br>
This shot:<br>
<img src="http://imageshack.com/a/img37/5811/dsc05123y.jpg" alt="" /></p>
<p>Was made using single softbox (of exactly the same size as yours - 60x60cm), no reflector, white backdrop, white walls, in a room about 2x3m in size, with a softbox almost to the face of model. If the shadows are too deep, use reflector for fill. Use the othe light for rimlight instead of reflecting it from the wall. In such a small room you'll have plenty of fill from light reflected off the walls anyway. Like here:<br>
<img src="http://imageshack.com/a/img266/6217/dsc05675editediteditedi.jpg" alt="" /></p>
<p>Same room, same softbox, but with reflector just under the girl and extra hairlight from the left (barebulb).<br>
Also, you DO want to postprocess, and very much so. There's a limit of what you can do in the camera, and the cheaper the set the more limiting the limit.</p>