I expect you have connected your Solo to ethernet and you know the IP address?
suppose it is 192.168.1.10
in windows explorer you type and press enter
login name is root, leave the pasword empty.
Then, when you see the rootmap, in explorer go to "page" in tge menu and in the bottom of the menu it says something like "open FTP site in Windows Explorer". Then you can copy, move and delete files.
You can also download Filezilla, that is better, bcause then you can manage the rights of the files.
Code:
http://filezilla-project.org