"Hey all i am new in usa. i am very curious to know about how to get better job, how to improve credit history, such kind of things. so if any one that let me know i appriciate all answer."

I am not sure about your visa status;
If you are on F1 then concentrate on your studies. If you study hard and maintain good grades then you can apply not only for scholarship but also campus assistance ship. Never ever think of stying illegal.I have found so many Nepalese folks who have given up their studies and solely concentrated on work, who earn mere 8/9 per hour. This will do no good for your future. You will end up stying illegal in USA and will never get chance to frequent your native.
If you hold green card then things will be lot easier for you. Do what 'ekloyatri' has suggested you. His suggestion will help you to build your credit history. Once you have good/excellent credit history you can easily get loan from any bank to set up your own business. Currently i have found grocery store/gas station seems to be very profitable business for people like us.