I tried to make my own fondant. when I rolled it out, it stick to the surface even I put some cornstarch or sugar powder it still the same. It stick and cracked. Do you have any idea how to make fondant from scratch? Do i have to put some gum-tex to the fondant that i made?

Hi there,
What kind of fondant are you trying to make? Regular rolled fondant or marshmallow fondant. I believe there are recipes for both on the site.
Well some people roll out on powdered sugar or on cornstarch. I prefer to very, sparingly, almost none, use a tiny bit of Crisco and rub it into my work surface. I even put a smidgen on the rolling pin. Sometimes fondant also cracks because it was not kneaded enough. Many people allow fondant to rest overnight before rolling it out.
You will only add Gum-tex to it if you are trying to make the fondant into something that will harden up, not quite as much as gumpaste but similarly. For regular fondant you don't need to add this although some prepared fondants do have a bit of an hardening agent added to them.
My youngest daughter was taught in baking school, to use a bit of shortening or a tiny bit of glycerine on her work surface before rolling out fondant.
Hope that helps.
Hugs Squirrelly Cakes
Edited to add, if your fondant is cracking, try incorporating a wee bit of shortening in it to make it less dry.