Does Getting A Filling Hurt?

I'm 13 years old and just went to the dentist today to get sealant on my 12 year molars... Turns out one has a soft spot in it (or a cavity, I'm not really sure...wasn't paying too much attention) and needs to be filled. I think my parents are going to get the composite fillings, but I don't know the difference other than colour. I looked up if it would hurt or not and all I saw was that they numb it and it doesn't hurt. Except the needle. So how much will this 'needle' hurt?? Enough to make me flinch? I'm really really really REALLY scared. I'm a big cry baby too... So, how much does it hurt? And the drilling too...? I don't think it's a big cavity. They didn't notice until they were about to seal it up. Also, what exactly do they do in this procedure. I NEED TO KNOW EVERYTHING. I want to be ready to face this and don't want to be suprised. I know this is long and as you can tell I'm FREAKING OUT. So please please please please PLEASE help me. Thanks a billion!