If you are in the US, the first step is to submit a FAFSA financial form. (You can do this in October or soon after for the following academic year; the earlier, the better.) You must do this EVERY YEAR you want to attend school... not just once (your eligibility may be different every year). When you submit the FAFSA, you must indicate (by using a code) which school(s) you are thinking of attending.
FAFSA does not award money. They analyze your finances, based on what you tell them, and they then determine two things: 1) Whether or not you are financially eligible for federally-based financial aid (certain student loans and Pell grants, etc.), and 2) How much money you/your family is expected to contribute to your education for the academic year in question. This amount is referred to as EFC - "expected family contribution".
FAFSA then sends this information to the schools you indicated on your application. Assuming that you actually apply to attend these schools, EACH SCHOOL then evaluates your application for admission and, if you are admitted, decides what aid to offer you. They refer to this offer as a "financial aid package".
They begin by estimating the cost of attendance (and housing, if applicable), and deduct the EFC. The remaining amount is your "unmet need". Then, depending on how bacly thy want you, they will try to meet that need. Each school's offer will be different, because the cost is different at each school, and because some schools have more money to offer than others. Your financial aid package, depending on your specific application, may include merit scholarships, skills scholarships (one of my friends got a full-ride BOWLING scholarship!), merit grants, need-based grants, tuition waivers, subsidized student loans, non-subsidized student loans, work-study employment, and so on. You are free to accept any, or all, of this aid. For example, if you already have a good part-time job, you may accept grants and scholarships, but decline the work-study employment. If you don't want to take out student loans, you can accept the grants and scholarships and work-study, but decline the loans. You can also take out the loans, but not the full amount. For example, if FAFSA and the school says you are eligible for a $5,000 loan, but you determine you need only $2,000, you don't have to take the full $5,000.
Of course, if you decline part of the aid, it is up to you to figure out how to get the money for the rest of the cost of school.
If the school can offer enough aid to meet the unmet need, your "final" unmet need will be zero. If they can't offer enough aid to cover all your "unmet need", they will list exactly how much "unmet need" remains. If so, it is up to you to figure out how to get that money.
Then, you compare the financial aid packages for each school and decide which school to attend, and what aid to accept/decline. I urge you to attend the school that will result in the least amount of DEBT...and I urge your parents NOT to co-sign for any loans.
Be aware that the school reserves the right to change the amount of the awards at any time. For example, if your state usually offers merit grants or scholarships, but your state legislature slashes the budget, they may have to withdraw part of the offer. (Once you get it, you're okay... but things may change in following years.) Also, the awards are based on what you indicated on your FAFSA submission. For example, you may be awarded a certain amount of aid, based on your intention to attend "full-time". If you then change to part-time, they will adjust the amount of the award(s) downward. Also... if your GPA drops below the acceptable limit (usually, 2.0), you will be placed on academic probation and will be INELIGIBLE for financial aid until you raise your cumulative GPA. Also, if you drop a class, you may be required to repay the money for that class. Also... if you are convicted of a crime involving drugs while you are in college, you will be PERMANENTLY ineligible for federally-based financial aid.... And so on... You need to LEARN THE RULES.
I urge you not to accept financial aid at all to attend a school unless it is REGIONALLY ACCREDITED. There are some schools out there that create their own "accreditation agencies" to make students and their parents THINK they are accredited, when they really are not.
Finally, make sure you thoroughly understand what you are accepting, and whether or not it must be repaid. If so, make sure you understand the conditions under which any outstanding debt may, or may not, be deferred, or placed in forbearance... and the difference between the two.
Finally, there are also external sources for financial aid... community organizations, churches, civic societies, and so on. Advice: apply for every scholarship for which you MIGHT be eligible. Every year, scholarship money goes sits and is not awarded to anybody, simply because nobody applied for it.