Theme problems

I am a noob of themes for phpbb.... i found all of these themes I like and I downloaded them. I looked for info no how to put it in your forum but they said use remote access and they weren't detailed enough (complete noob-friendly) . so if someone could please tell me how to add a theme in great detail I would appreciate it. Thanks (i am an admin)

Your theme must be in bbtheme format in order to import it to your forum.If it isn't then you can manually changed all the icons and buttons on your forum with the one the theme has. If that theme also has a CSS file you copy the codes from it and add them in admin panel=>Styles=>Pictures and colors=>Colors CSS Stylesheet tab.

How do you know if your theme is in bbtheme format? And I read the tutorial on the CSS and I find that to be a little too time consuming.