Assuming your friend is not in the US.....
First she must get in touch with the Board of Nursing of the country of origin if she is eligible to take the Nursing exam. She must pass the test and become a licensed nurse of that country.
Then she will need to pass the CGFNS exam. All foreign nurses need to pass the CGFNS exam to be able to apply for a nurse position in the US, except for 3 states (?).
Once she passes the CGFNS, she will need an employer from the USA. Some countries have recruiters for nursing placement in the US. Beware of scofflaws. I strongly recommend checking with your Labor department.
If hired by a US employer, she will need a working visa, passport, proof of employer sponsorship, etc. Once in the US, she will be granted a "graduate nurse permit" good for one year by the state's Board of Nursing. During this period she will need to pass the NCLEX (US nursing licensure) to be able to continue employment status as a nurse. If she fails to pass the test after a year, she can lose that job.
But if she is already in the US, she should get in touch w/ the state's Board of Nursing if she qualifies to take the NCLEX.
That's my limited knowledge but hope it helps.