devorced in Germany, both parties German, how to make legally valid in the state of Nevada

If I understand your question correctly, you do not need to do anything.  In the U.S., unlike many countries in Europe, there is no procedure to "register" with the State a marriage or divorce entered elsewhere to make it "legal" here.  If it is a legal divorce in Germany, and both parties participated in the process there, it should be recognized here if you ever needed for it to be.  If you happened to be in Nevada, and for some reason needed a court to recognize your divorce, the process would be to get a certified (or apostille) copy of your decree from Germany, and a translation, and then "domesticate" it in Nevada.  But, again, that is not necessary -- every U.S. State, including Nevada, should recognize you as single based on the fact of your German divorce.