First, go to the document page.
It should look a little like this:
You can search by Date from, Date to, Tags and/or just do a general Search.
If there is a Date from then only documents uploaded on or after that date will be shown.
If there is a Date to then only documents uploaded before or on that date will be shown.
If there are any Tags then only documents with at least one of the selected tags will be shown.
If there is any text in search, only documents with the whole text as a single block in any of the fields will be shown. This can be the File name, the Description, Document tile, tags or even a field on another document entity.