If Liferay is not running, then go to command prompt, as administrator, navigate to:
To create a portlet, use the command prompt, as administrator, go into
create.bat usc-test "USC Test"
This will create a directory usc-test-portlet that you can edit.
To deploy, in the same directory run:
ant deploy usc-test-portlet
It should go through the process. If it says build fails with this message:
[copy] Copying 1 file to C:\Apache\liferay-portal-6.1.0-ce-ga1\deploy
Target "usc-test-portlet" does not exist in the project "portlets".
But it actually does not fail, in fact it is deployed.
To add your portlet, login to the portal, and in the top bar you should see
+ Add -> More… -> Sample -> USC Test
If the portlet is already added and you are making edits, simply refresh the browser (it may take a few seconds to deploy).