Well learning php's object model is quite a bit out of the scope of this forum. We deal we issues directly relating to the OCI8 libraries for php so this is not the right place to ask that sort of question.
As to CURL...
Again this is not the correct place to ask that question; however, that being said, CURL is a general purpose tool for fetching web content without having a browser. There are command line versions and in addition it has been ported into many scripting languages such as php, but also exists in Python, Ruby etc. There many quite excellent tutorials for CURL. Remember when all else fails google is your friend.
If you have a question that deals with PHP's interaction with the Oracles OCI libraries we are happy to help.