Adding a .php page to a theme

Hey everyone,
I’m brand new to this.. I run a few sites, but have had other people do the developing (I basically do the writing). I’m wanting to do things on my own, now, or at least try. I have my own hosting plan set up through dreamhost. That being said, I do some affiliate sites, and I have had a developer create a cloaking page for me. What I want to know how to do, is how I can copy this page he created (when I go to the Appearance>Editor, it’s a .php page on the right side) and utilize it in my other sites. I don’t know how to add a .php page to themes. I’ve read that you have to do it through your host, and I did download Filezilla, successfully logged in, yet there’s no “wp-content” folder in existence there (and this is for a site that is up and running using wordpress, hosted on dream host).

I feel like this isn’t clearly put, but my thoughts aren’t clear at all. To put it like someone who has no idea what they’re talking about (which I don’t-so bear with me and try to think like a newbie)… how can I get another “page” full of code into that right hand area once you get into the editor on wordpress.

Also, I am using “responsive” theme, and want to edit the basic rule for the font colors. Anyone know how I’d go about that? I run another site where I was easily able to figure out how to do it, but the coding on this one is a bit different. That may be too broad a question to be able to be answered. If so, understandable.

Really appreciate any help you guys and girls have to offer.

Sorry for being ridiculous.