Where should i put this activities?
I have some academic extracurriculars, but I don't know in what section should i place them because the places where I have developed this learning are international corporations, also i have paid for this learning experiences.
I would consider those as non-paid internships because you worked at an International Company but were not paid, rather you paid for the opportunity to learn with them.
In college, depending on where you go, there are similar types of opportunities for students. At some schools, the student signs up for an internship but the company doesn't pay for the opportunity. In some programs like Stanford University one, the student is given a grant say up to $6,000 to cover expenses while they work for free at the company to gain work experience and subject matter knowledge.
Hope that is helpful.