KTT is a program that lets you transcribe text written in Roman letters into (and from!) the Tengwar (the Elvish letters) using Daniel Smith's Tengwar TTF fonts (or compatibile).
Dan Smith's tengwar fonts have very specific keymapping — the keyboard layout is (generally) based on the J.R.R.Tolkien's Tengwar chart found in Appendix E of “The Lord of the Rings”. There are two reasons for this:
The Tengwar is a generic quasi-phonetic alphabet — letters do not have fixed phonetic values. They can be and are re-defined by different races that use them to write their own languages. That's why for most of Tengwar letter there can't be one fixed place on the keyboard.
Many of the Tengwar letters can be represented by multiple versions of a symbol. So there's sometimes many Tengwar letters to represent one English letter.
This keyboard layout is very sensible and worldwide accepted, but on the other hand typing the text with Tengwar font gets quite difficult. And that's why you need transcription software like KTT.