codeigniter中的paypal付款方式

Question

I had posted following data to my paypal function in codeigniter controller

**Array
(
    [firstname] => firstname
    [email_id] => [e-mail]
    [address] => abc phase
    [select_country] => 1
    [select_state] => 1
    [select_city] => 1
    [zipcode] => 233234
    [address_same] => 0
    [shipping_address] => 
    [select_country3] => Select
    [shipping_state] =>abc 
    [shipping_city] => abc
    [zipcode3] => 123456
    [user_id] => 41
    [shipping_charge] => 50
    [grand_total] => 13569
    [quantity] => 1
    [payment_mode] => 1
    [submit] => submit
)**

i need to redirect my grand total and required data to paypal official link

https://www.paypal.com/cgi-bin/webscr

what all i need to post ..?

please guide for further procedure