adding to my root folder?

I would like to ensure that my website is regarded as safe by visitors to it, but it has a question mark beside it. 

 

When i went into the Nortons page, it said to add a code, which i got easily, so no problem there, but then i was to add it  to my root folder and i have no idea where my root folder is?  My website was from fasthosts who give you a simple template and i just loaded pics etc .  I dont have a clue about the root folder.

 

My website is www.nattyglass.co.uk

 

Please help!

 

Siobhan