Yeah, as Rico said, you just go to Custom, then Startups, choose one of the startups, click your countries, and run them.
The only thing to add is that you have to have logged into your countries (otherwise it doesn't realize you have turns) and you have to have the turns available. Meaning if you ran your first 20 turns, I don't think it'll work.
I pretty much always either use the all construction sites one or the farmer one.
fluff your 300 Spartans fool - i have 32 of the biggest fluffed mother fluffers made of titanium !!
A brigade from Blackstreetboyz (#91) has invaded your lands! Your defenses held against the invaders and forced them away! Your military lost:1 Troops