Help please!

Okay so I am a step mom, I met my step daughter when she was 4 years old and she has always been with her mother but with us on the weekends, she is turning 8 years old in August and my stepdaughter does not know how to read, she tells me her mom has her sit there with books just telling her to read and not showing her and that she yells at her for not knowing how to read, we’ve talked to her mom about this and we are keeping her this whole summer break, I haven’t had kids before and don’t know how to teach her to read, my husband works a lot and gets out pretty late. Is there any tips you guys can help me out with to teach her how to read?