why is H = {www | w ∊ (0,1)* } not regular language
You can use the Myhill–Nerode criterion. Consider the words $0^n1$ for all $n$. These are pairwise inequivalent since $0^n10^n10^n1 \in H$ while $0^m10^n10^n1 \notin H$ if $m \neq n$. Since we have found infinitely many pairwise inequivalent words, it follows that the language is not regular.

As mentioned in the comments, you can probably also use the pumping lemma, but it might take more work.