The homepage of Tahoe-LAFS is http://tahoe-lafs.org. There is a one-page overview at About Tahoe-LAFS.
This has been verified to work on Windows, Mac, OpenSolaris, and too many flavors of Linux and of *BSD to list. It's likely to work on other platforms.
WARNING! There are a few third-party libraries that Tahoe-LAFS depends on that might not be easy to set up on your platform. If the following instructions don't Just Work, please write to the tahoe-dev mailing list where fun, friendly, hackers will help you out! You might also find clues in the Advanced Installation section below.
Check if you already have an adequate version of Python installed by running python --version. Python v2.4 (v2.4.4 or greater), Python v2.5, Python v2.6, or Python v2.7 will work. Python v3 does not work. On Windows, we recommend the use of Python v2.6 (native, not Cygwin).
If you don't have one of these versions of Python installed, then follow the instructions on the Python download page to download and install Python v2.6. Make sure that the path to the installation directory has no spaces in it (e.g. on Windows, do not install Python in the "Program Files" directory).
Download the latest stable release, v1.8.2:
http://tahoe-lafs.org/source/tahoe-lafs/releases/allmydata-tahoe-1.8.2.zip
Unpack the zip file and cd into the top-level directory.
Run python setup.py build to generate the tahoe executable in a subdirectory of the current directory named bin. This will download and build anything you need from various websites.
On Windows, the build step might tell you to open a new Command Prompt (or, on XP and earlier, to log out and back in again). This is needed the first time you set up Tahoe-LAFS on a particular installation of Windows.
Optionally run python setup.py test to verify that it passes all of its self-tests.
Run bin/tahoe --version (on Windows, bin\tahoe --version) to verify that the executable tool prints out the right version number.
Now you are ready to deploy a decentralized filesystem. The tahoe executable in the bin directory can configure and launch your Tahoe-LAFS nodes. See running.html for instructions on how to do that.
For optional features such as tighter integration with your operating system's package manager, you can see the AdvancedInstall wiki page. The options on that page are not necessary to use Tahoe-LAFS and can be complicated, so we do not recommend following that page unless you have unusual requirements for advanced optional features. For most people, you should first follow the instructions on this page, and if that doesn't work then ask for help by writing to the tahoe-dev mailing list.