What about starting with grants. It is a path which opens doors to getting funds for your program.
Best of Luck,
As for the citizenship part of your question, if I am understanding it correctly, I believe that many progressive churches and refugee resettlement agencies offer clinics to help with the application process. You might try looking to those places.
What a big heart you have for these low-income students. Have you searched for religious organizations? Many of these organizations support education in third or developing countries all over the world from---charitable donors. I don't know if this idea would work but you may certainly give them a try---they might write you a onetime check donation and write-off. Though, I do see your compassion spirit for these children, I'm sure you are also aware these students can be educated in Public School throughout the state of California---Tuition Free. In fact, it's within the law to educate them---below poverty or not. I'm sure your not-for-profit organization needs funding to educate these children---a similar situation we have today in public schools, nationwide---K-12. Depending on how serious you are on this project, your organization may want to consider borrowing money from banks---at least to fund your program. See suggestion.