Hi and welcome to the forums.
Your first step should be getting a credit report from each CRA. You can get one free, annually, at https://www.annualcreditreport.com/cra/index.jsp.
Go over each report throughly. Only dispute what obviously should not be there, like duplicate accounts and accounts that are too old to report.
You can read the links in my signature to get a start on understanding the processes, abbreviations, etc.
If you have any questions, feel free to post the accounts, leaving out personal information. If there are a lot of them, I would make separate threads so it won't make it too long.
