Before going any further though, you MUST have initialized Holochain on your device. Do this using
$ hcadmin init your-email@address.com
Replacing your-email@address.com with an email address that you're willing to identify yourself within Holochain applications as. You will only need to do this once after installing Holochain.
Now you can join the Holochain app. You need to change directories into the folder containing the the code which is the EXACT configuration of the app that you want to join. If the code, or the DNA, differs in even the tiniest way from another user's version of that code, you will actually be running a different app. Run
$ hcadmin join . app-name
The .is a reference to the current directory, assuming that's the Holochain app you want to run. You could run the command from a different directory, and modify that path. The app-namecan be set by you to what you want, but you should give it a descriptive name. Now, to run the application, run
$ hcd app-name
This will start the app, and you can access it and start to see activity of your own, and your peers, by using the UI at http://localhost:3141.
Commands to reference: