How to post 3rd party HTML codes to display on my WP theme site?

Ok I have a question that may require some advanced support.
Im trying to get a “Buy Mp3s Table” **iFrame** onto a default template page on my site, and I don’t know where to post the HTML code.
When I use the normal page editor, Its set up like a blog post, and any code I paste will just display the characters after I update.

I tried to look in the “html editor” but I can’t find the place It would post correctly on the page I want.

**Here Is me trying to get the code to work on the normal page editor**

**and this is what it looks like on the other end**

How, and Where do I post the code So it will display on my site?

here is the site: (the page I want it to display on)
My Site

And here is the code:
<iframe width=100% height=80% src=”https://www.psalmplace.com/plugin.php?u=146&#8243; frameborder=0></iframe>

Its just a table of some mp3 files for download, mirrored from their origin so you don’t have to leave my site in order to download them.

Slightly Less important information:
I used wordpress and elegant themes to create a website for my wife because of how great (and professional) the themes look!

we recently uploaded a few of her demo songs on a site where people can pay to download them, and the admin was gracious enough to create a code that basically mirrors her Mp3 table onto our own site, so people can just buy it strait from her site.

She got her first solo contract to perform at a concert In a few weeks, and we need to get this code on the site ASAP.
It is an “iframe”.

Please respond, at least informing me that you don’t know so I can find alternate options, instead of waiting please.