Development environment

Hello.

I'm trying to brand our site, and found this tutorial on the web:

http://msdn.microsoft.com/en-us/Office365TrainingCourse_Lab_8_1

We have Visual Studio licenses, however we don't have on-premises Sharepoint licenses. For what I understand I would need to install Sharepoint 2010 on my development machine to be able to code a solution for sharepoint online.

Is that correct? Do I need an on-premises license to install Sharepoint 2010 on my machine for development purposes? Where would I download the software?

Thanks.