\b Anything after a ; or # that is not in a parameter (i.e. in quotes or part of another string) is treated as a comment. (i.e. "File myfile ; this is the file" would work)
\b For parameters that are treated as numbers, use decimal (the number) or hexadecimal (with 0x prepended to it, i.e. 0x12345AB), or octal (numbers beginning with a 0 and no x).
\b To represent strings that have spaces, use quotes.
\b To extend a command over multiple lines, use a backslash (\\) at the end of the line, and the next line will effectively be concatenated the end of it. For example:
\b If a file named "nsisconf.nsh" in the same directory as makensis.exe exists, it will be included by default before any scripts (unless the /NOCONFIG command line parameter is used).