I want to shift to Australia.

Before shifting to Australia i want to visit Australia first after then i can decide is it okey to shift or not. So i have already ask my friend to send me invitation letter, who live in sydney. I don't know what i need to submit to apply for visa? please let me know visa requirement to Australia for Nepali. My friend who live in Australia is going to sponsor me and on the way to send me invitation letter. I really want to shift to Australia not for luxurious life but for the future of my future childs because i was just married and i don;t want to have same things happens to my childs. I have planning to have child after 5 years so, i am planning now for future. What you guys suggest me?