You have reached the chrome page about xpcellml_api (part of the xpcellml_api distribution). xpcellml_api is a package providing access to the CellML Context and CellML API from the Mozilla Platform. It does not provide any user interface. For that, you will need to install another package, which will use xpcellml_api as a back-end.
xpcellml_api comes with some unit tests. You can run these tests by clicking here.