what do you mean upload product ? you mean create a new product (insert name, map category...) on the web by registered users ?
If so, then i don't think it's the right way to do, simply just go to your admin, and create a new role e.g staff and assign it the permissions to log into the admin and Product module (admin/Configuration/Access control list), then assign the user you want to have Staff role (admin/customers)
yes i want to add new product from front end not from admin view as the look and feel will be different . say i want link "add new product" i will enter some data and save then this product appear in products.
that would require a lot of code, you have to write it yourself by following the code from admin. However, it could break all security purposes, and i never do such a thing.