confused

[Michael Mossey]

Hello,
I'm trying to understand a basic task in Mercurial, but I'm having a 
hard time making sense of the documentation. I don't have any 
familiarity with version control systems and it seems like there isn't 
really any terminology explained from first principles, and my question 
is a little too complex to get relevant hits on Google.

I have a desktop and a laptop, and sometimes I work on the desktop and 
sometimes on the laptop. I just want to move changes from one computer 
to the other using Bitbucket to make the transfer.

I created a repository on my desktop. I followed the directions on 
Bitbucket to push the repository into an empty repository on Bitbucket. 
There was a warning that this would overwrite any existing data. That's 
fine because this is the first time I moved the code into Bitbucket.

I made some changes to the code on the desktop. now I want to get the 
changes into Bitbucket. Is this a "push," "pull," "pull request," or 
something else? I don't want to "push" because of the warning that it 
would erase any existing data, yet I can't seem to figure out what else 
it would be.

Then I want to download the changes from Bitbucket to my laptop. Is this 
a pull? Do I have to clone the bitbucket repo first? Is this an "update"?

Thanks,
Mike