How can I start to be a DJ?

I am 15 and don't have much money to buy equipment. I use a MacBook Pro with Djay software that let's me mix and record stuff from itunes. I don't want to buy fancy mixing boards or anything. If I plan on using this software at my school dance, How can I get speakers to connect to my laptop? I will probably be able to borrow amps and speakers from my school band, but, how does it work? USB cable? And, also, how can I plug into the speakers and plug headphones in to listen? Thank you!How can I start to be a DJ?
This is an interesting question. First and foremost you can not hook up dj/band speakers to your laptop and have the sound any louder and your laptop would be unless you are using powered speakers which have amplifiers built into them. Most bands do not use powered speakers though so you will need an amplifier designed for amplifying sound coming in and sending it out to a speaker(s). I have never tried it but in theory you could use an adapter to go from your laptop headphone jack to a dual rca plug and hook it into your amp. I would not recommend trying this however as you risk damaging your sound card. Plus it would be extremely difficult to control your volume without a mixing board. As far as plugging headphones into speakers you don't want to do this if you plan on having any hearing left after the dance. If you would plug your headphones directly into a speaker you will have the same volume coming into your headphones as coming out of the speaker. In the end you need a mixer. The mixer will control the power coming into your headphones as well as the power coming from your speakers. You will still not be able to cue music though unless you have 2 sound cards.