Create a monitor from Explorer

The simplest way to create a monitor is from Explorer, by using the Monitors menu on the metric chart.

Open the Monitors menu.
Choose + ADD.

The Monitors menu button's location and label depend on the metric:

For a non-sliced metric, the Monitors button is between the incidents button and the Actions menu (three vertical dots), in the upper right of a chart.
For a sliced metric, the Monitors button is on the upper right of the page, just to the left of the Actions menu.
If there are no monitors yet, the Monitors button will be labeled 0 Monitors.
If there are multiple monitors, the Monitors button will be labeled with the number of monitors, ie 2 Monitors.
If there is one monitor, the Monitors button will be labeled with the status of that monitor - Live, Paused, or Training
This If there is already a monitor on the metric, the Monitors button will be labeled with monitor status.

Lightup opens the Add monitor modal which has two tabs: Threshold or Anomaly Detection. The two tabs are shown below:

Threshold monitor

Choose Threshold if you want to specify the expected values.

Fill in Upper Threshold Value to specify the max acceptable value for your metric, and Lower Threshold Value to specify the min acceptable value. Any value between the upper and lower will now be considered "ok". Values above the upper threshold or below the lower threshold will cause incidents to be generated.
Click on the bright blue square if you want to ignore one of the thresholds. For example, any value above n is ok, put n into Lower Threshold and deselect the upper threshold by clicking on the blue box to the left of Upper Threshold.
Change Type to Percentage Change if you want to create a threshold monitor based on percentage change. In this case you will be prompted for the period - choose one of day over day, week over week, or sample over sample. In this case, the threshold values specify percentages. In other words, if you set Period to day over day and set Upper Threshold to 20, an incident will be generated if from one day to the next, the change in metric value is greater than 20%.

Anomaly monitor

Choose Anomaly if you want Lightup's anomaly monitoring to detect incidents when the value of the metric is outside of its historical range. The monitor will train using metric values from the last month, and will generate incidents if metric values are found to be anomalous, based on that training. While training is underway, you'll see the default training period listed.

When training is finished, the default training period becomes a link you can click to edit or delete the period. You can also add training periods of known-good metric behavior— just click + and enter the dates. (You'll need to save and train again to use the new training periods.)

Perform additional configuration

Monitors have additional configuration options. To access them from this modal, click Manually configure monitor at the top. This takes you to the form that allows you to create a monitor manually.

Set up notifications

If you want your monitor to send notifications, you can select a notification channel where they should be sent. The channel needs to be set up already. For details on setting up an integration for notifications, see Add an integration.