Click on the folder that contains the files you want to move.
Hold the CTRL key and the letter "A" key. This will select all files in that folder. You can deselect specific files by holding only the CTRL key and clicking on the specifc file with your left mouse button. Once all the files you want are highlighted, click any one of them with your left mousebutton, hold the button and drag it to the new folder location.
Good luck,
Peter