How can I use Python to log in to a website and perform actions in it?

How can I use Python to log in to a website and perform actions in it?

These are the steps I need to automatize:
1) Log in
2) Select an option from a drop down menu (To acces a list of products)
3) search something on the search field (The product we are looking for)
4) click a link (To open up the product's options)
5) click another link(To compile all the .pdf files relevant to said
product in a bigger .pdf)
6) wait for a .pdf to load and then download it.(Save the .pdf on my
machine with the name of the product as the file name)
I want to know if this is possible. If it is, where can I find how to do it?