In some countries it is easy to get an American visa. In some countries it is very difficult. It may be easier to get a visa if you also apply for and recieve tentative acceptance. Tentative acceptance means that when you finish the Preparatory English Program you will be able to study at Northwest Missouri State University. If you ask for tentative acceptance, you will know if you can study in the university before your come to the United States.
Tentative acceptance is only for undergraduate students.
Students applying to graduate school cannot get tentative acceptance. To see if you can get tentative acceptance, you should try to enter Northwest Missouri State University now. If you get tentative acceptance, you will get a letter from Northwest Missouri State University telling you that you may study in the university. You should take this letter with you when you go to the American embassy to get your visa.