Getting a working visa for Australia from Nepal is not easy, however, it is not impossible as well.
If you are a highly skilled professional or a business person who is in demand in Australia, then you can apply for a skilled visa using SkillSelect. However, you may need to participate in a skill assessment test.
You can try employer sponsorship visas. In many cases, SkillSelect is not required to apply for this type of visa.
There are three types of employer sponsorship visas. They are temporary work visa lasting from one day to four years. Employer Nomination Scheme visa and Regional Sponsered Migration Scheme visa where your visa duration is permanent.
There are other types of visas Australia provides such as First Work and Holiday Visa and Second Work and Holiday visa open for persons between 18 and 30. Unfortunately, these visas are not open for Nepalis.
The best way to get to Australia would be on employer sponsored visa. You just need to apply for Australian jobs online. If you are selected, you then apply for visa processing. If you get the visa, you can certainly leave for Australia on a working visa.