I just purchased a Minecraft account, and I'm only able to play the demo version

I just purchased a Minecraft account, and I'm only able to play the demo version.

You need to message customer support. We can't help you here mate.

Maybe you could download the minecraft software or whatever it's called, you know the thing where you can access it from your desktop? I don't know, have you downloaded the new minecraft startup thing? Sorry, I'm terrible at remembering what these things are called, but basically when you run minecraft, it will show a crafting table icon at the bottom of your screen (the taskbar) instead of a grass block. If not, then just do what the other person said and contact customer support.