You cannot upload Mods for Dashpanel here, they must be uploaded using tools the game developer has created, so the files can be verified. For more information see guides written for this game. Here are the instructions provided by the game developer:
Select your dashboard in the user saves tab of DashPanel. Press the upload button (Cloud with up arrow) First time you may need to authenticate via email key. Fill in details on Upload Layout dialog. Press the Submit button.