Im following the video guide isoccer made (Great vid!) but when i come to the create district part:

I put out the corners, I write "//expand vert".

But when I try to write "/te add district " it says:

"An internal error occurred while atempting the command"

I have a town (i wonder if i have to "refound" for the plugin to work)

Can anyone help me?

What you have right now is a region where you built a 'Settlement'. You have to make a pe to have it turned into a town (The mod has to make the regions using MCTowns). Make sure you either remove any and all regions within your town or tell a mod that there is more than one, because this will cause conflicting permissions.

So, remove the plots?

I really don't want to answer this without looking at the regions myself. What is a warp to your town and I'll take a look and get back to you.

Danni told me to go here instead so..

The warp is /warp hstown

Have a look