Hi everybody, happy new year!!

I made a website recently: www.malthus.ws and i used Sitebuilder, but i would like to develop my website (it's in french), like i want to add new pages...etc but i dont want to lose the Sitebuilder's design of my website. I tried to use NVU (freeware) but i don't succeed to keep that design.
If someone uses NVU or another freeware to make his website, can he (or she) try to help me please ( i'm french but i can understand english  ).