That's going to be dependent on your servers. It should bet the same way you upload any files to your site... FTP would be the most common, but could also be something like SFTP. If you were to upload anything to your site now, how would you do it?
Should just be the root of the folder where your public files are for your website. It should give you the URL where it's looking for it at. What is the domain?
Sorry, I don't know anything about cpanel... if you are having trouble uploading files to your website, you would want to contact your hosting company. They should be able to tell you how to upload files on their servers.
If the WordPress dashboard allows you to upload files to your server, then I don't see why it wouldn't work. But I would think it would be easier to upload directly (the same way you got your WordPress files on your server).
Once again google did what its best at. Here you go this should be pretty straight forward if you havent already figured it out..
That's great. I couldn't find a vid like that (perhaps embarrassingly). If that's all there is to it, I'll try it.