What can I do for my boyfriend to be here in the US if he is from Dominican Republic?

If you want to get married, do it. There is no requirement to show valid immigration status to get married. After marriage, you might be able to ask the government to give your husband a green card. Here are the conditions: 1) you have to be a U.S. citizen; 2) you have to have income that will keep your family over the federal poverty level ($20,025 if you have no dependents, plus &5,200 for each dependent); it has to be your income, not including your husband's earnings; if your income is not enough, your husband will need a co-sponsor (a U.S. citizen or permanent resident who has income to support his own family plus one, and would promise the U.S. government to take care of your husband if he becomes unemployed, ill, or disabled or needs support for any other reason; until your husband becomes a U.S. citizen, he will not have the right for welfare, foodstamps, Medicaid, subsidized housing or any other public support) 3) your husband has come to the U.S. legally, with a visa, and never left since; 4) your husband does not have any criminal convictions; 5) your husband was never deported, given voluntary departure, or given a notice to come to court and failed to do so. If *ALL* these conditions are satisfied, your husband has a good chance of getting a green card. If there is a problem with any one of these conditions, talk to an immigration attorney to find out whether the problem can be solved.