Looking for a place to stay (Milan)

Hi everyone!...this is Sofia from Argentina and since I will be in Milano from the 8th of sept till the 11th of sept id like to know if somebody of you knows about a cool place to stay there, economic if possible and close to the main places to visit or even the train station that would be easier for me to reach for when i have to leave (kinna downtown). If possible, Id like to make reservations now in advance to make sure I have a place to stay by then which Im sure there will be lots of turists by then and could possibly be harder to get there with no reservation. Thanks so much!!

Greetings!

Sofia