need a php curl function

i will need a php curl function that i wish to add to my project. this is what i expect the function to do :- function($user,$pass,$stock_details,$price,$buy_or_sell) { // this is the web site it has to curl into " [login to view URL] " // this function should curl into the web site and place a buy/or sell order //each line in the function should be explained by comments, explaining what it does }