Hi.
Go to my computer double left click on the external drive this will open a new window and you should be able to see your files, if the new window is maximized make it smaller so you can see your desktop on one side.
Now place your cursor over the file you want to move press and hold left mouse button and move the cursor onto a space on the desktop and release the left button, that’s it.
You can use the same procedure to move the file anywhere on your C: drive i.e. My Photos or a new folder.