Step by Step Install of MAAS and JUJU

From what I understand in the comments, it sounds like you just have one server, which you have installed MaaS on.

Having MaaS installed on a server doesn't just let you run VM's on the server using the MaaS API (interface). What MaaS does is let you manage other physical servers from the MaaS server, using the MaaS API.

You can build a setup where the MaaS server manages virtual machines and you can use those virtual machines using the MaaS API, but this would be used more for testing MaaS out than for production -- there are better systems (that don't involve MaaS) to use for running a bunch of virtual servers on one physical machine (like LibVirt and KVM or even LXC, which I hear Juju has and is continuing to work on their support for).

You might look at How do I configure juju for local usage? if you are wanting to just be able to deploy Juju charms That method would bypass using MaaS, and instead use something called containers (also referred to as LXC) that should let you deploy charms to the local computer but with the charm in it's own sandbox.

Installing Local Cloud Infrastructure using Ubuntu 14.04 LTS MAAS