Hi Syruss,
If you're already got a .war file and you want to deploy it there are a couple options.
1) From the Control Panel, you can use the Plugins Installer portlet. There should be a tab that says Upload File which will allow you to browse your local system for a war file.
2) Drop the war file in the hot deploy directory. By default, there is the
deploy folder in the Liferay Bundle. If the server is running, Liferay will pick up the war file and deploy it.
If you're using the Plugins SDK, then the
ant deploy target should deploy the portlet to the correct location. If you are using a non-standard hot deploy folder location, you may need to modify your build.<username>.properties file to point to the correct path. Look at the original build.properties for a section that looks like this: