install non WP website

Hi, hello, I will not tell now, that i am a dummy in websites, because of my question sure everybody will know, LOL. but thanks for this opportunity to ask here.

I have a PPV Chat site with an Script from video whisper under WordPress installed. Because of certain reasons i could not get in friendship with WP, so i made a website on my PC with Corel Web Creator. After hours of searching i finally found out how to upload and did all upload to the ftp account i extra set up for this. (inside /public_html/ as folder ftp-new) Now I dont know how to change the current theme with the site i did, for now the homepage would be enough , since the other pages are not ready. I dont want to overwrite something i need for the videoscript. I used the same menu units like in the now installed theme from WP, and for now it would be fine when I could at least change only the front/homepage. thank you for helping