You can add additional metrics to any table by scrolling down in your table options and selecting the blue lettering that says "+Add Metric"
After selecting "Add Metric" you should notice a shimmer over the top element dropdown (if you have minimized this dropdown, you will need to maximize it now to see this). This shimmer is indicating you are now adding a metric to this table, *not* the dashboard.
Pro Tip: You can confirm this by checking the text in the top right corner of the dropdown menu.
This navigation should look very familiar to the previous navigation you used to select your first chart. Select any new metric and you will see if plot in a new color on your table.
Once you have added multiple metrics to a table, you can re-order how they display by dragging and dropping the metric cards under the "Metric" section of the table options.