NSIS for starters

A few options:

1. Read through source for existing apps
2. NSIS Support pages
3. NSIS Developer Center

Yep, Help File too. The NSIS manual is a good one.

Try to find some source that is commented well, so you can figure out what it's doing while you learn the syntax.

If you know something about batch files, it will be easy. NSIS itself quite a simple "language", the more complicated stuff done with plugins (like system calls, registry manipulating).

First, you may want to download NSIS itself, than examine the shipped source code examples, they are quite good for a starting point. I suggest HM NIS Edit (http://hmne.sourceforge.net/) for editing NSIS files, it's a sort of IDE for NSIS.

I use HM NIS Edit for its InstallOptions (GUI) form designer. All the rest I use GVim for.

Having learnt NSIS, I found most of it not hard, but the Modern UI documentation is woeful, especially for event-handling. At the moment I'm contemplating writing a PHP/HTML/jQuery/jQuery UI NSIS script builder... Maybe after I've finished my last Yr 11 exam for this semester. (Advanced General Mathematics, just about to go.) I'd intend it to have an event-based UI builder, for easy form-building, but that probably wouldn't help too much with launcher building for portable apps.