I have a few shouts that I have learnt but it wont allow me to use them and comes up saying I need a dragon soul to use it. I have captures a few dragon souls since I learnt these shouts but still unable to use it. Do you need a certain soul to use certain shouts?

To unlocked a shout, all you need to do is half one dragon soul for each of the 3 words you wish to increase. If you look down at the bottom right of where your shouts are listed it will tell you how many souls you have, and depending on which platform you play on( for instance I play on xbox) it tells me to press "X" to unlock the shout.