Go to the "Download" tab (to the right, or use the Downloads tab above) and click on the current release to download a zip file containing all of the binaries you need to run Boogie. Please let us know if something doesn't work!
After you download the Boogie zip file, you'll need to tell Windows to unblock its contents. To do that, right-click on the zip file, select Properties, click the Unblock button, and click OK. You can then unzip the contents into the folder of your choice.
You need some underlying prover to run Boogie. We recommend Z3 (of which you'll need version 4.1 -- newer versions are currently not supported), see the old Z3 page
for download/installation information. Note, Boogie will find Z3 if you install it according to the default settings in the Z3 installer. However, if you have a copy of z3.exe in the Boogie binaries directory, Boogie will prefer that copy. You can use Boogie's /trace flag to see where Boogie is getting Z3 from, and there are also command-line flags for letting you specify a different location (see /help).
Apparently some people persist in using a 1970s operating system. If you are one of those unfortunate people, then Zvonimir Rakamaric
has written a tutorial
on how to run Boogie under Linux.