Oh, don't be nervous, it's really simple....honest!
When you've done it once you'll wonder why you worried.
First time best thing is just to nip a bit off the end of each nail. Then gradually take a bit more off over a couple of weeks till you get them the length you want.
Not only is this less nerve wracking for you but it's less likely to cause bleeding. When the nails get long the quick inside gets longer too so nibbling them back causes it to retreat back up the nail.
Don't panic if you happen to draw a little blood first time. It isn't life threatening!
A stiptick pencil, from the chemist that men use for shaving nicks, will stop the bleeding quickly But it will stop anyway.
Just be brave & do it, it's not as bad as you think.