A grant is a sum of money which is given to a college student, with no fees or upfront costs. You are not required to repay the money. A loan must be repaid, with interest, usually at some point after graduation.
Most grants are available only to those seeking an undergraduate degree. Most also require that you be enrolled full time in an accredited college or university.
The best place to start your search for a grant is at the Federal Student Aid website. You will need a copy of your last year's tax return, or that of your parents, if you are under age 24. At the end of the process, you will be given an EFC number. This will tell any college to which you are applying how much federal aid you should receive in the form of a Pell Grant.
Most colleges and universities also offer grants themselves. Private schools frequently can afford to offer more in grant money than public ones, often simply due to state regulations. Once the amount of the Pell Grant is determined, schools will put together a package for you to accept or reject; the rest of the tuition and fees must be covered by loans or cash.
Doing an Internet search on "grants" or "scholarships" can be exhausting and fruitless. There are, however, websites which consolidate this information and these can be useful. They typically ask for basic information, interests, location, and so forth, and match you up with possible providers.
Avoid any companies or websites which promise "free" money and also require upfront fees, or any fees. Many use the word "scholarship" but require no information regarding your previous transcripts or grades; many send bulk mailings to prospective students "congratulating" them on their prior successes. Another common scam is an invitation to attend a workshop to receive "insider" information. None of these are legitimate.