Complete Newbie to Web Apps, how can I get my app to render?

So I’m writing a web app for the first time , and I’m having troubel getting my app to render the HTML file that contains a scheduler. I’ve downloaded the scheduler folder with all the samples, and when I open a sample HTML, it loads in my browser fine.

However, when I route my GET in my app, and point it to one of the HTML files contained in the sample files, it tells me that scheduler is not defined when it calls scheduler.init(…

Any Idea how to fix this issue?

It seems that js file of scheduler is not located correctly.
Check the path in script tag to the dhtmlxscheduler.js and try to open it directly in browser.
If you are using some framework ( ruby, yii, etc. ) - js files need to be placed in assets folder to be accessible.