include content within conditional statement?

You can do that via echo, just place it on a new line inside the if conditionals braces { and }

e.g.

if(this statement is true)
{ // <- do everything between here
     /*
     stuff that happens if the statement is true
     */
} // <-- and here

else
{
     // stuff that happens if the statement is not true
}

So you could do this:

if( is_page( 39 ) ) {
    echo do_shortcode('[nggallery id=1]');
    // add more stuff here, e.g. echo "<p>Bio info etc</p>";
    echo "<p>Bio</p>";
}