Tableau offers a 2 week free trial for all of their licensed products. Tableau also offers licenses to Students for free here and nearly free Desktop licenses for non-profit organizations here.
To get started with a free trial, navigate to Tableau Products to see a list of their offerings which include:
Desktop products will run on Mac OS and Windows 32 and 64-bit versions.
Server runs only on Windows.
Once you have downloaded your desired product, run the installer and start building viz when complete.