How can I get afull PhD donation from USA
You mean a scholarship for a PhD, right?
well, to be honest I'm not exactly sure because these things depend on so many factors. Each organization has its own specific requirements, not to mention that these requirements are also different from country to country.
Right now I'm a Master's student in the US, but I came here on my own account, and it costed me a lot of money.
One way to do it is to go through the university itself rather than a scholarship from an outside organization. Look for universities that can give you a job on campus while studying, I've met many people who went to the US for a PhD and they were working in their departments while they were still studying. These jobs will give you enough income to live and pay for your tuition as well.