You are probably seeing this page because you installed the OpenMRS Platform, and saw a nearly-empty screen that linked you here, instead of the EMR you were expecting to see.
Starting with version 2.0 the OpenMRS Platform does not include a built-in user interface. The rationale is that this will enable people to build all sorts of different OpenMRS distributions, using completely different web technologies to build different user interfaces. However this can be confusing if you installed the raw OpenMRS Platform, but you were looking for a full OpenMRS Distribution (like the Reference Application).
If you are a "typical" OpenMRS user and you are looking for a complete OpenMRS application, you probably want to remove this installation, and replace it with one of the out-of-the-box OpenMRS Distributions (like the Reference Application).
If you're sure that you want this version of the OpenMRS Platform, and you want to add a community-supported user interface on top of it, you have a couple options:
If you are already running the OpenMRS Platform, then you need to add quite a few modules to be running the full Reference Application. You can get these by going to http://openmrs.org/download and looking for a link like "Download Reference Application (version number) Addons". (Make sure to get the version of the reference application that corresponds to the platform version that you are running. Unzip that file, and put all the OMOD files in your modules folder, and all the OWA files in your owa folder, and restart the web server.
Get the latest version of the legacyui module from the OpenMRS Module Repository
Go to https://addons.openmrs.org/#/show/org.openmrs.module.legacy-ui-module and download the latest version.
Get the latest version of the legacyui module code