If you're on a very tight budget & don't care about the car too much, and it's not a big leak, then some of the pour-in-the-radiator "leak stop" products might work quickly Something like this. Raw eggs (or just eggwhites) might work too for a little while. Those would coat your entire coolant system with "goop" that should plug small holes.
But best is to find exactly where it's leaking from & repair that part, I'm not familiar with that model, and google's been unhelpful about your particular model. Could just be a gasket between two metal parts, maybe thermostat gasket if lucky, or could be a cracked part. North American Toyotas often have the thermostat attached to one of the radiator hoses that connects to the engine. And the thermostat gasket is a rubber "ring" around the thermostat that is easy to replace, and also easy to accidentally twist (creating a leak) while replacing too.
Youtube is a good place to start & see how it's generally done (but LOTS of the "backyard mechanics" there are terrible & do as much damage as repairs ;-)
This video about replacing a thermostat looks somewhat professional (from "Supercheap auto", not counting the 70s xxx music) and might be generally helpful, but even when they scrape off the old gasket you could scratch the metal & cause leaks if you're not careful. A plastic or soft metal (copper?) scraper would be safer than a steel razor.
General precautions would be:
- Don't touch or take apart anything if it's hot, you could get badly burned.
- Drain the coolant (usually from the drain cock on the bottom of the radiator) before taking apart anything, otherwise the coolant will spill everywhere.
- Have another method of transportation available, in case you take apart your car & need to buy something else before fixing it.
- Most coolant is poisonous, and also tastes sweet (how evil), so keep animals & children away and don't leave spills or open coolant lying around, (and don't lick your fingers if there's coolant on them either).