I have just learnt that I need to fill in the 1040NR tax form as I am receiving income in the US asI am renting out my summer apartment.
Can someone please advise where I can get detailed information on how to fill in the 1040tax form step by step?

Thanks you in advance !
Claudia

Are you a citizen or resident of the U.S. If yes, then you will file Form 1040 and schedule E.
If you are a nonresident, then you file Form 1040NR and Form E.