Custom Symbol Trouble.

I found a presentation by Mr. Matthew Lorono about custom Symbols in solidworks,

I try to create a New symbol for learn how do it, but i cant save my new document .SYM for Load my Changes.

appear an alarm that says: access denied!

what i need to do for save my new symbol and how can use this symbol.

Thak you.

i am stuck with save the new Document .SYM.

SolidworksDrawings And Detailing