Read html file,Insert data,Output a file

Hi,
I tried to read the document java.io.*. There are so many different classes and methods to use. For the beginner, I am confused. Could you please recommend the best way to code. If you have sample of code, that would be great.
I have an HTML file that needs to be read and remember to the point of the “” tag, then insert new data and finish reading the rest of the file and output to a new file.

Thank you very much,
Nhan Nguyen