need help with a sed script

[Nathan England]

I absolutely just do not understand sed...
I have a ton of files and scripts I've collected over the years. Through the 
course of time I was adopted and my name was changed, now I am changing it 
back to my original name and I want to change my nme in all my scripts... 
this is lame and tedious no doubt, but something for fun.

All my scripts are located in a series of folders contained under my Documents 
folder. Basically, I need to find every file that contains the word 'England' 
and  replace it with 'Aubrey'

Can someone help please?