If you save/download a picture from someone else's facebook will they know about it?

[<3]

I want to borrow a picture of my friend from her facebook. we want to use it on her surprise b day cake and we don't want her to know we are using it. It says you can just click and save to your computer, but it downloads it on my google chrome. i'm worried that she'll get a notification that we stole her and pic and she'll ask why and we'll have to tell her about her b day party early. should i be worried? will it notify her, or will she be able to tell? there's only a few days til her b day!
thanks for all the helps so far!

it looks like i just have to right click and save...then it saves it to my computer. from there i can print it out, or have it scanned. i just need a print out to give to the lady at the cake store. she also said i could e mail it. thanks!