Boot into Mint, and when the Desktop is open .....
- Click on Computer to open that Folder
- Click on Windows
- Click on Users
- Click on the folder with your Username (the name you usually log on with)
You now have access to your profile in Windows, and you should be able to navigate as you would do if you were booted into Windows
- Navigate to the files or folders you want to transfer
- Right click on the file or folder and select Copy
- Right click on your Linux desktop and select Paste
Be careful not to delete anything when you are inside the Windows folder. Linux does not "respect" any Windows permissions, and will happily delete anything you ask it to, even System Files, without prompting you.