Here a link to youtube tutorials about the Umlaute: https://www.youtube.com/results?search_query=die+deutschen+umlaute Umlaute are mutated (or secondary) vowels, sometimes as well written as 'umlaut' in English.

ä as a in anger ö as ear in early ü as ew in stew without st

Well, that is difficult to write. Best would be to watch a video about the pronounciation of ä, ö, ü.

@Eduardo: Have you already figured it out? I just tried to pay attention to what happens in my mouth while pronouncing ÄÖÜ. Which seems to be: When pronouncing A, O, or U, the tongue stays at the bottom of may mouth, and for ÄÖÜ it moves upwards until the sides of the tongue touch the upper teeth. So for "Ö", just try to say "O" and move the tongue up. Did that help? ;)

German Wikipedia sums it up as follows: – ä = [ɛ] (also [æ] or [e]), äu/eu = [ɔɪ] – ö = [ø] or [œ] – ü = [y] or [ʏ] https://de.wikipedia.org/wiki/Umlaut#Artikulation_in_der_deutschen_Sprache