"Megan Parker keeps running to check her mailbox, she is waiting for a letter from my cousin."
Correct version
"Megan Parker keeps running to check her mailbox. She is waiting for a letter from her cousin."
As an English speaker the advice i give to someone who wants to learn English would be it does take time but it's actually not that hard to learn English you just need to keep practicing and try to talk with the words you know so you can get used to it.
