Try This One...
<connectionstrings>
<add name="ApplicationServices">
connectionString=
"data source=.\SQLEXPRESS;
Integrated Security=SSPI;
AttachDBFilename=|DataDirectory|\aspnetdb.mdf;
User Instance=true"
providerName="System.Data.SqlClient"/>
</add></connectionstrings>
<system.web>
<authentication mode="Forms">
<forms loginurl="~/Login.aspx" timeout="2880" />
</authentication>
</system.web>
After This U can Use Membership...
<system.web>
<membership>
<providers>
<clear />
<add name="AspNetSqlMembershipProvider">
type="System.Web.Security.SqlMembershipProvider"
connectionStringName="ApplicationServices"
enablePasswordRetrieval="false"
enablePasswordReset="true"
requiresQuestionAndAnswer="false"
requiresUniqueEmail="false"
maxInvalidPasswordAttempts="5"
minRequiredPasswordLength="6"
minRequiredNonalphanumericCharacters="0"
passwordAttemptWindow="10"
applicationName="/"/>
</add></providers>
</membership>
<profile>
<providers>
<clear />
<add name="AspNetSqlProfileProvider">
type="System.Web.Profile.SqlProfileProvider"
connectionStringName="ApplicationServices"
applicationName="/"/>
</add></providers>
</profile>
<rolemanager enabled="false">
<providers>
<clear />
<add name="AspNetSqlRoleProvider">
type="System.Web.Security.SqlRoleProvider"
connectionStringName="ApplicationServices"
applicationName="/"/>
<add name="AspNetWindowsTokenRoleProvider">
type="System.Web.Security.WindowsTokenRoleProvider"
applicationName="/"/>
</add></add></providers>
</rolemanager>
</system.web>