What´s the difference ´u´ and ´ü´ pronunciation? (Like su and süt)

Say i (like in English tea), keep everything as it is inside your mouth but make your lips round and you get ü.

http://www.tslguide.com/grammar-vocabulary-pronunciation/pronunciation/letters-harfler/

use this to learn how to pronounce letter

I pronounce ´ü´ as ´oo´ isn´t it right..?