For learning Nepali language it is necessary to know alphabets in Nepali. You have to know alphabets in Nepali to learn writing in Nepali language. Nepali alphabets are the building blocks of Nepali language. There are 48 characters in Nepali alphabets. Nepali alphabets are made up of Nepali vowels and Nepali consonants. The Nepali alphabets contain 12 vowels and 36 consonants. Nepali vs German gives a comparison between Nepali and German alphabets.
Nepali script is also known as Nepali writing system or Nepali orthography. The set of visible signs used to represent units of Nepali language in a systematic way is called Nepali Script. The Nepali language uses Devanagari i.e. Nepali alphabets are derived from Devanagari script. The script decides the writing direction of the any language, hence the writing direction of Nepali is Left-To-Right, Horizontal. Learn Nepali Greetings where you will find some interesting phrases.
Is Nepali hard to learn? The answer to this question is that it depends on one's native language. One should start learning Nepali language with Nepali alphabets and Nepali phonology.
Time taken to learn any language that is mentioned here is the approximate time required to learn specific language for the person who is proficient in English. You can also go through all Indian Languages and find if Nepali is one of the language of India.