Once you've ensured that the capacitor is sufficiently discharged, you can measure its capacitance.

Turn the function dial to the resistance/capacitance mode and press the blue select button to toggle on the capacitance mode.

Touch the probes to each end of the capacitor to make a measurement.

Even though the electrolytic capacitor may be polarized, it doesn't matter how you connect the probes during the measurement.

If you're measuring a capacitor on a circuit board and you're not getting a proper reading, the capacitor may be in parallel with other circuit components. You'll need to desolder or disconnect one end before measuring the capacitor.