The proof materials for studying abroad vary according to the country you choose and the course stage you study. Generally speaking, people who go to English-speaking countries need to pass the IELTS test and get corresponding results, and the performance requirements are different. If you are a non-English speaking country, you generally need to master the language of that country.

If you want to go to college, I suggest you start preparing from the second year of high school. First of all, you should prepare for the language test required by your country. Second, you should prepare the corresponding application materials, because it will take some time from the application notice to the application for a study visa.