You have to create your own town,
This means you need to mark out a 200x200 area that doesnt go into anyone elses town, mark the 4 posts with A B C & D. :)
You can edge the whole town with something like cobble as well to make it easier for the Staff who make your town.

Then get the co-ords from each corner where you placed the signs and then create a Mayor App :p
Oh and make sure you have enough funds :)

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To be able to Town Claim a existing town, you need to be Tycoon Rank :)

 

@Mission001 u forgot the 15 block rule

 

He doesnt have to be 15 blocks away from someone,
He will just need permission from the neighbouring town owner if he is :p