Graded Readers would be best to start out with as they will use simple grammar and will often be accompanied by pictures to help you in guessing the context of sentences for things you don’t know.
This thread is a good source for reading materials:
If you want to dip your toes into graded readers without having to pay the weight-in-gold price commanded by some companies this is a good source:
They won’t be as fancy as the professionally written and illustrated ones, but can give you a good start.