How do I create a credits page for the inclusion of music and sound effects? Specifically those at soundimage

There are a few ways of doing this. One would be using a separate room, called when the player has completed the adventure, probably involving a wait command or a keypress command listing all the people you'd like to thank.
Personally, however, I'd prefer to attach a credits option to the 'Help' command. This would involve modifying the 'Help' command, probably something which should be done for every game.

There is a page that 'The Pixie' made which has the 'Help' command as a pop-out.
https://textadventures.co.uk/forum/samples/topic/5111/how-to-modify-the-user-interface

The important bits of which are below:

To Activate Code.

	In Start Script:
OutputTextNoBr (game.stuff)

	Change Help Command:
JS.eval ("$('#dialog_window_1').dialog('open')")

To be pasted into the game object immediately after the line 'first published'.

<stuff><![CDATA[
<div id="dialog_window_1" class="dialog_window" title="Help">
<p id="page0">Welcome to <i>UI Example</i> help system. Click the buttons at the bottom to see different stuff!</p>
<p id="page1" style="display:none;">Click on an object or person in the lists on the right to see what actions you can perform with them.<br/><br/>If you are reading this, you probably already found the <i>HELP</i> command, with <i>LOOK</i> and <i>WAIT</i>.</p>
<p id="page2" style="display:none;">Just try clicking stuff. Seriously, how hard can it be?</p>
<p id="page3" style="display:none;">Created by The Pixie.<br/><br/>Thanks to Alex Warren for creating Quest, and to members of the forum for various bits of code, in particular The Pixie for this interface stuff (bits of which originate with Jay Nabonne).<br/><br/>Feel free to use and abuse this in your own games!</p>
</div>
<script>
function setPage(page) {
$('#page0').css('display', 'none');
$('#page1').css('display', 'none');
$('#page2').css('display', 'none');
$('#page3').css('display', 'none');
$('#page' + page).css('display', 'block');
}

$(document).ready(function () {
$('#dialog_window_1').dialog({
autoOpen: false,
height: 400,
width: 640,
buttons: {
"Intro": function() { setPage(0);},
"Commands": function() { setPage(1);},  
"Hints": function() { setPage(2);},  
"Credits": function() { setPage(3);},  
"Done": function() { $(this).dialog("close");} 
}
});
});
</script>
]]></stuff>

This is the method I use in my games.
Hope this helps.

Store this script in a game attribute. Say...
game.soundcredits

msg ("<br></br>Game creation by Robert Hatfield, using the \"Quest\" program created by Alex Warren. This game uses music and sound effects by Soundimage.")

Then call it in any script with:

do (game,  "soundcredits")

That's my method!

Forgewrite. I was able to create the script without problems, but I can't find out how to write a script call in Quest.

Just create a command with the pattern:

credit;credits;about