Great question; it is good that you are looking into ways to obtain financial aid. No one wants to end up with loads of debt after finishing college. The most common way to obtain financial information is to apply through FAFSA, which can be accessed through fafsa.ed.gov. After entering financial information, you will get to see a package of of financial aid offered in a few months, which could be through loans or grant, which are provided by the school and/or government. The package may vary by the schools.
If you are currently a high school student or a student at a community college, the career center, or counselor should have information on scholarships that the school is offering for a 4 year university. I definitely recommend applying for scholarships/grants that are applicable to you, you would be surprised on how few people actually apply .
Another option is to just search of scholarships and grants online. Usually the prompts will require an essay, which is worth your time to potentially get a big chunk of money. From what I remember, sometimes the prompts of various scholarships are very similar. In addition, if you have a particular 4 year university in mind, research into the financial aid offered, and apply for any scholarship/grants.
I know this sounds like a lot of work, but it is worth it. Just think about potentially how much financial aid you can obtain from writing a few essays and doing research, which will reduce stress and the cost of a 4 year school.
Hope this helps,