Templates

I have a domain name hosted at HostGator.com.
I want that site to be a blog,their cpanel has “Fantastico”.
My problem is that I have a template on my computer I want to use.If I use “Fantastico” it only gives me the default or the classic version.
How do I replace them with my template?
I can’t just upload the template to my public_html.
So how do I solve this problem? I have no tech skills but I can follow instructions.Can someone help me with this?

Gaetane:)