Regularly refer liferay's good forum and it's conversation.
connected with liferay current news and events,
"www.stackoverflow.com" is good website for sharing and increase knowledge about the liferay programming.
hope my reply is helping you.
Thanks....
You can trying to search (like : server side programming java with c++) in Google books and refer some pages of available books,
after you got some good book than go through it.
According to reference of http://www.liferay.com.
Liferay provides two main ways to develop applications.
1.Portlets
2.OpenSocial Gadgets
Portlets are small web applications written in Java that run in a portion of a web page. The heart of any portal implementation is its portlets, because they contain the actual functionality.