Graphics Help please photoshop

I have never used Photoshop so can anyone help me out with the following

I have worked out how to edit the psd template so that the menu names are what I wish them to be my problem now is how do I save them to the image folder so that they overwrite the old image. Oh I have taken a copy of the origianl site just in case I make a boo-boo.

Any help would be appreciated.

your can private message me if you would be so kind, I will reply but please note that I reside in new zealand so time zones do become a factor

thank you in advance.