for hungarian team:
<connectionStrings>
<remove name="LocalSqlServer"/>
<add name="LocalSqlServer" connectionString="Data source=.;AttachDbFileName=|DataDirectory|\ASPNETDB.mdf;Integrated Security=true;user instance=true" providerName="System.Data.SqlClient" />
</connectionStrings>
if you use the asp.net membership provider you have to use this connection string .
other countries: use./sqlexpress as data souce but the process is the same