For learning Oriya language it is necessary to know alphabets in Oriya. You have to know alphabets in Oriya to learn writing in Oriya language. Oriya alphabets are the building blocks of Oriya language. There are 42 characters in Oriya alphabets. Oriya alphabets are made up of Oriya vowels and Oriya consonants. The Oriya alphabets contain 11 vowels and 31 consonants. Oriya vs German gives a comparison between Oriya and German alphabets.
Oriya script is also known as Oriya writing system or Oriya orthography. The set of visible signs used to represent units of Oriya language in a systematic way is called Oriya Script. The Oriya language uses Bengali, Odia alphabet (Brahmic) i.e. Oriya alphabets are derived from Bengali, Odia alphabet (Brahmic) script. The script decides the writing direction of the any language, hence the writing direction of Oriya is Left-To-Right, Horizontal. Learn Oriya Greetings where you will find some interesting phrases.
Is Oriya hard to learn? The answer to this question is that it depends on one's native language. One should start learning Oriya language with Oriya alphabets and Oriya 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 Oriya is one of the language of India.