CNA course in the USA typically takes about 3-4 weeks to study plus 1 week of clinicals at a nursing home or hospital. Judy is right. Some hospitals will even train you for free as long as you are willing to work for them. But someone has to be I the USA to do the CNA course
As for the registered nurse, you need to already have the nursing license from the government of Kenya, the best way is to go through recruitment agencies like Avant, MedPro etc, they will vet the nurses qualifications, grades etc and they will pay for you to do the NCLEX including airfare to South Africa etc. Then once they have passed the NCLEX, your CV is forwarded to hospitals, and once the hospital interviews and hires the nurse, then the embassy gives the nurse a work visa.