Can you connect to your ftp site? The code will need to be saved into a html file before it can be copied to your ftp site.

Generally I have lots of of PSD (photoshop) files that are different web pages on my web page. But how do I upload these to my domain? Do I just publish them using filezilla?

Hi,
What is facebook conversion pixel? if it is related to your website then Just login with your ftp account. if you don't have create a ftp account from cpanel of your hosting. After login you upload html folder (html, css, slice images contains) inside public_html directory. then check url if it works. If needed i can help you.
Contact me at Fiverr
Thanks.

You can take help from a designer like Designs2html Ltd. They know about your problem and have instant solution to it.

Now a days website HTML conversion is very popular all conversion is will doing HTML coding also.