Labels are a handy way to organize your documents after you upload them. If you haven't created any labels yet, create some from the Labels panel first.
Once your case has labels, there are two ways to apply them.
Drag and drop. The quickest way is to drag documents onto a label in the Labels panel in the sidebar. To label a single document, drag its row onto the label. To label several at once, check every document you want, then drag one of them onto the label.
Edit Labels icon. Check the documents you want to label, then click the Edit Labels icon (the tag icon) in the document grid header. A dialog lists the case's labels, each with a checkbox.
Check or uncheck labels to add or remove them, then click Apply. A checkbox with a dash means only some of the selected documents have that label — check it to apply the label to all, uncheck it to remove it from all, or click it once more to return to the partial selection.