But as being 14 years of age, do I need anything to be carer for her? Or she can just stay with me?

Hi everyone. Need some advice and information. I’m from Latvia and lived in UK non stop since 2005. I’ve got younger sibling from my mum second marriage, she is 14 years old. She is citizen of Latvia. What do I need to have so she can come other to us here and live and study?
Thanks