Create Popup

Depends on where you want the popup to come from and what triggers it, and what you want it to look like.

I agree with Zach, there are a lot of dependencies on what you're asking.

Just a simple popup, trigger would be just when a user first loads page for it to start automatically.

you can do it as simple as a javascript alert https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_alert (bad user experience)

but if you want the pop up to be styled you will be getting into more complicated things.

Where do I paste the script in Kentico? I am not familiar with this CMS yet. I am well versed in basics like Wordpress etc.

The link Zach provided was a sample of how you can trigger a popup. On the right hand side it renders the output. If you hit the "try it" button twice Firefox browsers already will give users the option to block this type of pop-up.

Meaning it's a bad (simple and quick) but bad solution.

If you can't share the requirements I'd suggest you ask your vendor to explain how the estimation is build up because you think it's quite a lot of money.

Any developer, agency or product should be able to explain to you why things costs what they want to charge you...

It might be your installation needs to support 200 different devices, or you want it on a page that already has 20 popup's behaving differently, or any other complication that might factor in...

I just need a simple box window popping up telling customer about a promotion like 20% today only etc.

It does not need to be supported by 200 devices nor do I have any current popups or a complex page for that matter. Very basic.

All I am looking for is the most simplistic modal box popup on page load.

Ok I figured it out using this code:

https://pastebin.com/M2fHRZ4a

However only issue now is its loading in the bottom right and not in center of the screen/

https://imgur.com/a/5MiC89l

I'd still advise you to contact your vendor.

Anyhow I found your page and this is mainly caused because you've inserted it into an H2 (used for title or something). Which two divs higher is forced to a certain margin.

if you move your code to (for instance) the first thing on the page you'll get something like:

Our vendor charges us for everything, so the point of me trying to figure this out was to avoid being gouged by the vendor, which we are unhappy with.

With that being said I think our access to the site is very limited as I cannot modify most of the page templates, theres only 1 or 2 editable sections of the page I can actually work with.

Where should I be going to insert it at the very start of the page? I don't think I have access.

Thank you also very much for your help and time!

Sounds like you need a new vendor! If they have set your side up like that with such limitations then you probably don't want them as a vendor any longer. The point of a CMS is for you to be able to edit pretty much anything on the site whenever you need to.