Drag and drop files using touch pad

I used to be able to click on a file without it opening, then hold down on the touch pad, and drag the file to a new window. Now, clicking on the file simply (and annoyingly) opens it. Particularly when I'm, for instance, trying to move a photo from my download folder or desktop to an app like Mailchimp. Where do I fix this? I already tried touchpad in System Preferences. This process use to work (drag & drop -- not system preferences) and no longer does. Help please. thank you.