Ramcharitmanas is one of the greatest Hindu Scriptures, where the "story" about Ram (Lord Ram) has been written. It is said: Tulsidas was the reincarnation of great sage Valmiki; Valmiki wrote Ramayana. If we check both Ramcharitmanas and Ramayana, both convey the same story about Ram. If we compare in terms of quantity, Ramcharitmanas can be said the shorter version of Ramayana. Often, Hindu Gurus asked people to read Ramcharitmanas daily, as it supposed to help in spiritual progress.

For reading the biography of Tulsidas, check this Wikipedia link. And, to download comlete Ramcharitmanas, visit this "link" of Gita Press, from where not only Ramcharitmanas but you can also download Hanuman Chalisa and Bhagavad gita (all pages).