well if you simply required a login and other stuff for your game at local......
Simply create a database with tables according to your need.. for example for login.. you can create a table with columns like login name and password...
create a connection string in your page.. get the values of username and password entered by user in textboxes as text.. and check them with the values in database...if found appropriate allow or else error.. in the same way.. you can do the signup as well...
you can create a string.. get the values entered by user in textboxes and just save them in database table created for signup....
Hope that gonna help...
for reference see the links below...
http://www.w3schools.com/sql/sql_create_table.asp[
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http://www.techimo.com/forum/webmastering-programming/168066-sql-connection-string-c.html[
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