To upload a website from your computer to the Plesk server using File Manager:
On your computer, add the folder containing your website’s files to an archive (ZIP, RAR, TAR, TGZ, or TAR.GZ).
In Plesk, either click the "web folder" on top of the website description or click "File Manager" in the account features.
In File Manager, access to the desire folder path ( default and mainly httpdocs ). Click the + sign to Upload, Create File or Create Directory.
Once the file has been uploaded, you can browse your website to verify.