Possible sources of the water leaks are
The temperature pressure relief valve is located on top of the heater, water seeping from this valve is not a leak as such the valve is simply doing its job which is to release water when excess pressure is detected. Excess pressure can be caused by the thermostat temperature being set too high, a faulty thermostat or the main water supply pressure being very high. The valve itself may also be at fault. If you determine that this is the source of the leak you should consult a qualified water heater repair person because a build up of pressure could cause the tank to explode.
If water is dripping from the water pipes connected to your heater, use a wrench to tighten the fitting from where the water is leaking, dry the fitting and area below and check back later to see if you have stopped the leak.
The drain valve is located at the bottom of the heater, if it is leaking first ensure the valve is fully closed by turning the handle fully clockwise, if it does not have a handle and is the plastic type, take hold of the fixture and turn it fully clockwise. If after doing this the valve is still leaking, it is faulty and you will need to replace it.
If water is leaking from the heating element gasket, the gasket needs to be replaced, this is not a simple job and requires special tools, so it is advisable to seek the help of a qualified repair person to.
Water heater tanks have a limited life, usually around 10 to 15 years, leaks can start from anywhere on the tank and the cause is rust or corrosion, when the leak starts it is usually small but will gradually become worse, so as soon as it is noticed you should have the water heater replaced with a new one as soon as possible.