text file parsing

Hello, I have only been working with php for about 2 hours now so bare with me if I type something stupid. I am trying to open up a remote text file, parse the file, and output the parsed text as html. As of now I can open the file read characters into a buffer and then output them as html. My problem is with parsing the buffer to get to the text I want to output. Should I read the entire file into an array? Then output the parts of the array I want to show? If so please post some type of example code. Does php have functions to move through a file and choose which characters you want to put into an array or a buffer? Any help would be greatly appreciated. Thanks for your time