ORACLE!!!

Hello, I'm trying to connect to a Oracle Database on a remote server. I have read a lot of documentation but I can't connnect to the database, I dont have a very clear concept of what i need to connect to the Oracle database. I'm using Win2kPro / Apache / PHP 4.2.1 / Oracle 8i Client 8.1.5 In the phpinfo() OCI8 and Oracle modules loads perfeclty. In the documents I've read, I saw that I need environment variables, whats the purpose of those variables? What happens if I dont set the environment variables? Which are the environment variables? (i.e. ORACLE_SID, ORACLE_HOME, etc) I've using this kind of code, but it doesn’t connect me to the server. putenv("ORACLE_HOME=C:\Program Files\Ora81"); <-- Is this the home directory? putenv("ORACLE_SID=SID"); $connection = ora_logon ("user", "pass") or die("No Connection"); I really don’t know why I cant connect, in the SQL Plus I cant connect just by typing the user, password, and Host. Please TELL ME! Any help would be appreciated. Roberto Ramírez