Well there are different ways to dj using your laptop. A programme like Traktor will give you up to 4 virtual decks , a mixer , fx , loops , cues etc. This can all be controlled via hotkeys or much more commonly using a midi controller.This takes you away from the laptop and gives you some buttons to press and knobs to twiddle.
You can also control music files on your laptop by turntables/cdj's for the traditional feel but as you said you were new to it im guessing thats not what your after.
The other laptop route is using a programme called Ableton Live. This programme can be more suited to producers or those who want to do more than just play other peoples music. as you can sequence in midi instruments / sounds. Say you had made a track , you could have all the different elements and using Live, perform the track by sequencing it all together on the fly , or indeed remixing it on the fly.
It depends what stage your at really , how much you want to spend , how much time you want to put into it and what sort of music you want to play
At the lower end are programmes like Virtual DJ which i havnt looked at but im sure do a similar thing