It would be handy to know just what stobe light you purchased, but softboxes are fairly generic. Here's a pretty good overview of how they work and what you need:

http://www.firelily.com/photography/softbox.html

Hi Picsonly,
Here is a link to the Photoflex web site. They not only manufacture soft boxes, but they have free lighting lessons via their web site. They also have an 1-800 number where you can talk to a live person for purchasing advice.

http://photoflex.com/

The owner was a fashion photog prior to starting this business many years ago so they are very knowledgeable.

For a hairlight you may wish to look at modifiers tht are a bit more dirctional/controlable like a snoot, grid spot or barndoors.
While softboxes are fairly generic, the attaching/mounting rings are usually specific to the mains brand.

Chimera is the largest manufacturer of softboxes. They sell any size you can think of and speed rings (to attach) for all the most popular strobes.

But you should also consider using white umbrellas to soften the lighting. I have both and use whatever is appropriate for what I'm shooting.

White umbrellas are more practical for location shooting. I have a two umbrella/lightstand kit that fits into a small Bogen tripod case that can go anywhere.

What you do need to understand in choosing the size of a softbox or umbrella is that they only put out soft wrapping light if the distance from the subject is smaller than the diagonal of the front of the device. Therefore, the larger the better within reason.