Switch off the car and open up the hood. Make sure the engine is cold and not heated.
You will have to find the clutch fluid reservoir. This is usually located near the brake master cylinder behind the engine in most cars that have hydraulic clutches. However, the clutch reservoir is a lot smaller than the brake reservoir so it might be a little difficult to locate. It is ideal to have your car manual with you while doing it for the first time.
Once you have located the reservoir, you will need to check the clutch fluid level. The fluid should be above the marker or full. Remember, if you cannot locate the marker, just check if the fluid is filling up more than half of the reservoir. In most vehicles today, the reservoir is transparent but in older models it is not. Therefore, if you have any trouble with locating the marker, just keep in mind the above-half rule.
If the fluid is lower than the marker or is less than half of the reservoir, you will have to refill it. Also, check for any leakages that might be there. If you recently refilled the reservoir but it is showing low amount of oil then a leakage is in place.
Add fluid to the reservoir if the fluid is below the marker. Make sure to wipe any spills that occur.