Hi Ivan. In my experience, tablets kind of suck for this kind of thing—at least Apple ones. There are some web design apps for tablets, but I haven't had much luck with them.
So one option would be to sign up for one of the many online services that allow you to set up a free website, such as Weebly, Yola or Google Sites (there are tons more, though).
It's easier to play around with web design on a desktop or laptop computer. You can build a whole site and test it "locally" (that is, on your computer rather than over the web). Then you can upload it to the web later, if you wish.