\title and \author declarations and the
\maketitle command as usual.
SIAM journals don't put author affiliations below or beside
the author(s); instead, use \thanks to list addresses.
In fact, it is an error to use \\ in the \author
command, because it interferes with some fairly fancy
footwork that the style uses to change the author and title
to all uppercase.
If there are several authors with the same affiliation,
the best I can suggest is to \thanks only one, see
what footnote mark comes out, and manually place it after
the others (sorry).
The \maketitle can be followed by an abstract and/or a keywords
section, as shown in the introduction.