Do I need to know something specific before starting?

Hello Abril! Nice to meet you! Great to see LATAM participation here! :) I think that the first step is exactly has interest and you are in there moment. If you love your career, engineering for example, your passion will make easier each activity in your university and professional life. 
About the classes, it depends of what engineering you want but generally, the backbone has a couple of math classes, physics, calculus and statistics. Instead of programming skills, maybe logical skills, I mean can determinate a path to get some result in the easiest way. For example, if you have to find the 'x' in a formula, how you can solve the problem? Yes, you can find a lot of resources about how develop programming skills. 
If you want to start from scratch maybe can start here: https://hourofcode.com/es/en/learn And then, I suggest to continue in these sites: https://docs.microsoft.com/en-us/learn/paths/csharp-first-steps/ and https://docs.microsoft.com/en-us/learn/paths/build-dotnet-applications-csharp/
As a tip, if you have time, read blogs, technical blogs like my blog: Hello Shirivo! bit.ly/HelloShirivo
Finally, can follow me in different social media (if you have the “Minimum Age" to access) where I'm constantly sharing opportunities to learn: bit.ly/aboutshirivo
#shirivo

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Hola, Abril. No te preocupés, lo has hecho bastante bien, te dejo la respuesta resumen en español: estudiá bastante en el colegio, sacále provecho a los recursos gratuitos que te dejé arriba y no dudés en agregarme en las diferentes redes sociales (pedí permiso a tus padres y revisá que cumplás con la edad mínima permitida). Sobre si es compleja o 'dura' la carrera, pues tiene su nivel de complejidad como todas, pero si tenés la pasión y estudiás bastante, te ayudará a que todo salga bien. Si tenés alguna otra duda, escribí nuevamente. Un abrazo, #shirivo :)