NetperfMon won't monitor which user is logged into the system (you might check out our APM product for that) but you can alert on interface status as follows:
In the main menu click Alerts -> Configure alerts
In the Configure Alerts screen click the 'Net Alerts' button.
In the 'General' tab provide a name and make sure the 'Enable this Alert...' option is checked.
In 'Property To Monitor' scroll down to the 'Interface Status' section and check either 'Interface Status, Operational Status, Administrative Status, or Interface Responding ?'. Choose the one that best suits your needs. For this example I selected 'Interface Status'.
In the 'Monitored Network Objects' tab select the monitored interfaces that this alert will apply to.
In the 'Alert Trigger' tab select the status to trigger on and the status to reset on. For this example I will trigger when an interface is 'Unknown, Down, Shutdown, or Warning'. I will set the reset for 'Up'.
In the 'Time of Day' tab select the time period and days that the alert is valid for. i am leaving all settings in this tab as default which is all day every day.
In the 'Alert Suppressions' tab you can setup conditions to check before trigger the alert. I am leaving the default which is no suppression conditions.
In the 'Actions' tab click the 'Add Alert Action' button.
Select the 'Send as E-Mail/Page option and click 'OK'.
Fill out the Email recipients the FROM account and any SMTP information. You can customize the trigger and reset messages. I am leaving them as default. You can use the macros to indicate which interface, node triggered/reset which on which status. There are other macros you can use. Click the 'Help with macros' on the same screen for more information.