I have added a new custom extended field in audience manager contact creation window. But I want my custom required field on top of this screen. And Can we move my custom field to General tab.
The order is determined by the database. So if you can change the order there, you can have it show up at the top.
You cannot put it on the General tab, as that's for the built-in fields that aren't customizable.
Of course you could try to do something like that in a GUI extension, but I doubt it would be worth the investment.
(FYI, the next version will likely have the ability to move the fields up and down as you wish)
Please read the documentation about Custom Contact extension.