Silhouttes can be very creative and can also be elusive at times. The basic premise is that the subject is backlit with little or no light falling on the front of the subject. Abstract forms can be created, the entire subject can be shown, or just a little light can be allowed to hit the front of the subject. In the image that is shown in the blog, a lamp was reflected off of a white wall and the model stood in front of a sheer curtain. I took a meter reading off of the curtain to be sure that the model fell into complete darkness. In some cases, a tripod may be necessary for long shutter speeds particularly when using constant light sources.
The link below steps through creating a silhoutte using a studio strobe. The speaker walks you through several variations, and then takes his image into photoshop.
Which ever method you use, you will likely have to take your image into an image editing program to edit the image. I would strongly recomend flagging (blocking off) light hitting the legs of any lightstand that you may use. This will save time and frustration during the editing process.