The 3 most common options are through:

• Work - you need a US based company to sponsor you. Apply for jobs that offer sponsorship and relocation support. Or work for a company in your country that has an office in your desired destination, and ask to be relocated.
• Education - attend university in your desired destination.
• Marriage - fall in love with a citizen of your desired destination and get married.

You’ll have to get in through a visa based on the above categories, then apply for permanent residency once you’re in. Only after a few years of being a permanent resident can you apply for citizenship. Note that this can take years depending on the category and the country you’re from.