First find the leak:
If the leak is not evident this way you will have to rent or borrow a cooling system pressurization kit to cause the leak to reveal itself.
The repair will be dictated by what is leakingYou will have to locate the source of the leak before you can fix it. Re-post with your findings.
You have to determine the source of the leak then decide on how to fix it.
depends where the leak is, and how bad it is.
antifreeze leaking into the oil pan
Pressure test system to determine where leak orginates to determine fix
Find source and fix it.
Replace the thermostat gasket.
Have cooling system pressure tested to determine origination of leak
by getting a Bars Leakradiator leak at walmart
Coolant leak, possible heater core. Suggest to have it pressure tested to find leak.
It is possible. However, it will be a temporary fix.
A part has failed. Find where the leak starts, and fix that part.