How do I make a town and become a mayor?

You will become a mayor by making a town.  To create a town use the command 

• /town new <town_name>
• /town newgold <town_name>

For example to create the town with the name Xavier's Town you would say 

• /town new xaviers_town

The command /town new costs 500 gems and /town newgold costs 1000 gold.  If you create a town with gold there is minimum town distance of 5 plots.  If you use gems there is not minimum town distance.