how do we upload files from local server to web server via ftp

Answer 1

if you mean localhost to your server you have to use ftp protocol to send data and use curl to embed data with connection. like
ftp://yoursite.com
(note: your server must support ftp protocol for your site)
if not use simple upload system given by your webserver site like cPanel. or use filezilla.
even it not please explain your problem.

Answer 2

use ftp softwares like filezilla.