Fixing my credit score of 576

Please no judging as it was worse then that. How do I dispute things on my credit report ? Better yet what can I dispute ? Do I send a letter somewhere ? Do I email ?

Any1 have experience with this?

Let me add. I am paying over minimum payment on CCs. I pay my vehicle on time. I pay half mortgage (not on title) I have medical bills from a loss in August.

I am working on repairing student loans. Not sure how though