My rendition follows, with some notes for your reference:
Nai Heru alyuva’r hepuva tye, nai cendelerya caluva tyenna’r raina nauva tyen. Nai Heru queruva cendelerya tyenna’r antauva sére tyen. Násie.
"May (the) Lord bless-and keep you, may his-face shine upon-you-and gracious be to-you. May (the) Lord turn his-face toward-you-and give peace to-you. Amen.”
alyuva’r: contracted from alyuva ar “bless and.” When two like vowels appear together in this way, it’s common to elide them in speech. You’ll notice I elided a few instances in this prayer; these are all optional and can stand as separate words if you like. There are a handful of “bless” verbs in Quenya; I chose this one for its sense of “make prosperous.”
tye: Quenya, like Spanish or French, distinguishes between familiar/informal tye and polite/formal lye “you” in the singular. If this prayer is addressed to multiple people, le “you all” would be used in both contexts. Wherever you see a tye- form (tye, tyen, tyenna) in my translation, lye or le can be substituted accordingly.
Please let me know if you have any questions!