It would take a year to teach you all the intricacies of the written Elvish languages – there are two, and each are written differently.
The writing style on the One Ring is an ancient style, and different than, say, the Feanorian Tengwar you see on the Door to Khazad-dum.
Instead of giving a full lesson on how to write Elvish, I’m going to cheat and give you an Elvish generator.
http://derhobbit-film.de/rune_generator.shtml
When you use it, you’ll have the option of choosing
what they call “Hobbit Runes (Old English runes from The Hobbit)” (inaccurate on both counts – the map wasn’t a hobbit-made map, and the runes are Futhark, not English)
Dwarvish runes
And Feanorian letters – THIS is the Elvish Tengwar you want.
You can put anything into there, and have it transliterated into Elvish, but it is not a translator. The language stays the same, just changes the alphabet.
For an example of what comes out, I used it to transliterate Amin milya wanwie.