Hi,

SecurityTokenForFormsAuthentication  function obtains a security token for a user authenticating through forms-based authentication.

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spsecuritycontext.securitytokenforformsauthentication.aspx

Then get the MembershipUserCollection and foreach it.

MembershipUserCollection users=Membership.GetAllUsers();

MembershipUser objUser;

foreach (objUser in objUserCollection)
{

LastLoginDateLabel.Text = u.LastLoginDate.ToString();

}