If you are using a standard English keyboard, remember that you will also need a (like Tamil 99, Phonetic, or InScript) to type with these fonts. Alternatively, you can use on-screen virtual keyboards or transliteration software.
Upon downloading and extracting the NC Tamil Fonts Collection ZIP file, you will discover a well-organized set of TrueType (.ttf) and OpenType (.otf) font files, typically including: nc tamil fonts collection zip