When I have to put "TO" before a verb? Please explain me it, thanks

Introduce myself Hello everybody, My name is Gianangelo, but everyone call me Gian. I live near Bergamo, in the north of Italy.Bergamo is 60 Km from Milan. I'm married with Lorena (Lory) and we have two children. My first son's name is Mattia and he has five years. My second son is Fabio and he has 2 year. I work in a company that works for power plants in all the world.My job is tecnical designer. My English is little because when i was a student, I had some Teachers that were unqualified to lear me English. They were italian teachers but didn't speak english very well and so I didn't learn English well I would like to lear better English because I think that is too important for work and travel, in fact I staied in London and in the USA some year ago, but I didn't understand nothing. I hope to try someone that want help me. Thank you for attention. Bye bye Gian