First job or internship

Hello everyone. I'd like to ask if anyone knows if in Belgium is possible (legal)to do an internship in a company without being enrolled in the university, and of course being a foreigner (from Schengen area). I ask because in France is entirely illegal to have an internship if you are not registered at the university. I'm Spanish, bachelor and master in economics. I speak English and French. But I have no work experience related to my studies so I think the only way to get a job is by doing an internship first. If it is possible, do they use to pay something? Does someone has some tips to look for internships? If not, which are my possibilities to find a first job with 25 years old and no previous experience?