wordpress has it own opload tools for images and other 'media'.
But it uses ftp when you do an update.
What is not working for you?
thanks pzuurveen ,and I require ftp login via custom login form and then download the .txt file and display products in(.txt or .csv ) on wordpress site.or via simple php code how ican custom login into ftp
You can use any ftp-client to login to you wp-site.
Use the same username/password as when updating.
But if that cusom-form is on the same server as wp, you can simply use a simple webform to upload your products.csv
if not: ftp-put