Rosanna is wondering if she as a US citizen can sponsor her brother to immigrate legally to the United States and grant him permanent resident status. She says that she realizes that his brother is already in the US visiting her as a legal tourist and if she files USCIS forms I-130 and I-485 they will be able to adjust their status whenever their turn comes and in the meantime they will get work permits to work in the US.
Indeed, this is a common misconception that arises because of somewhat confusing language in the law that if the relative is already in the United States legally, she or he can adjust status after the petition is approved. The actual story is a lot more complex. You see when someone enters the United States as a tourist, the understanding is that they really plan to engage in activities common with a visitor, like visiting friends or family, or sightseeing. Trying to settle down in America shows bad intent and gives perfect reason for the USCIS officer to deny the application. This denial can even happen if the tourist and US citizen get married. For siblings, the denial is almost guaranteed, particularly on a B1 visa.
There are genuine cases, of course. A tourist who has been in the US for months happens to meet the right person and they decide to get married. They have a chance for approval but the questioning will be aggressive. For siblings or parents, adjustment of status from a tourist visa or other non-immigrant visas (like F1) are nearly impossible to execute. Actually, it is best to secure visitor visas for these family members prior to applying for an immigrant petition and establish a good record of timely departures. A visitor with a valid visa who has a pending immigrant petition can be denied entry at airport and the visa cancelled if the officer suspects that the visitor is unlikely to leave on time. If these people are already in the US on other valid nonimmigrant visas like F1 or H1, they can generally stay without any problem.