where can i upload documents for visitors to download?

Hello!

Thanks for the excellent question. 

Many document formats can be uploaded in exactly the same way as other media types, via the Media -> Add New menu. 

According to the WordPress Codex, the following document formats are allowed:

• .pdf (Portable Document Format; Adobe Acrobat)
• .doc, .docx (Microsoft Word Document)
• .ppt, .pptx, .pps, .ppsx (Microsoft PowerPoint Presentation)
• .odt (OpenDocument Text Document)
• .xls, .xlsx (Microsoft Excel Document)
• .psd (Adobe Photoshop Document)

By default, WordPress organizes your uploads by Year and Month, so, for example, anything you upload this month will be in the directory:

/wp-content/uploads/2019/10

Some third-party plugins are designed to make this process easier. For example, Easy Digital Downloads is designed to let you sell your downloads. Another one I found to help with folder organization is called FileBird -WordPress Media Library Folders.

I hope this helps!