Nail biopsy - can anyone tell me what to expect?

Hi,

I'm new here and just wondering if anyone could inform me what happens when you have a nail biopsy? 
I am scheduled for minor op next week, but have no idea what to expect...

For background, I have had a brown streak on my fingernail for several years now. Only recently saw GP who has since referred me.

Any info would be much appreciated.

Thanks in advance.