How can I narrow or broaden the forum?
ACP > Templates & Style > **choose theme** > global.css > choose '#container' from the drop down list > edit the 'Width' setting. Something like 700px for fixed width or 70% for a percentage.
And If I want broaden the space of box when I open a new thread?
What do you mean by that... can you be more specific as to what you mean by 'space of box'??
Smal uppp
Upppppp
That info would be in the forum>jscripts>editor.js file. Keep in mind changing it will make it look funky.
It's not ./inc/jscripts/editor.js at all, you need to alter the columns and rows of the editor textarea in the New Thread and New Reply templates.