I'm a noob with LaTeX. I've start two day ago, so please, be kind

I use LyX because I like the WYSIWYG thing.
I want that my caption fit the width of the figure. For that, I use the "Insert floating figure" menu, and I put the
\ffigbox[\FBwidth]
of the floatrow package manually with the ctrl-L command, between the \includegraphics
and \caption
.It works well. But I have a lot of figures. Is there a method to automate this ? I mean the use of
\ffigbox[\FBwidth]
. I've tried the macro from the 
Thank you. (sorry for my english
