Automatizing web browser form filling in Python
There are Python libraries and tools for automatizing browser actions. StackOverflow.com is not a place to ask for an recommendation for such a tool and thus moderators will close this question (SO is usually asking a help for particular problem, not for broad help and tutoriing requests). However here are some starting points for you
Mechanize - Python library for stateful programmatic web browsing
Selenium automizing framework Python bindings - using full installed browser
For installing Python packages please refer to official package installation tutorial.