Well, that's a challenge and a half. Since you're not in the US, you likely won't get in any trouble venting freon. Just try not to be seen.
If it's a house hold refrigerator, most of those run about 6 ounce of freon. What do you have for new freon, and any way to weigh it?
at this point, sounds like what I'd do with no tools would be to very quietly release all the refrigerant out of the fridge. Is your access valve on the small or the large line, or on the side of the compressor? If it's on the side of the compressor, or on the large line you can add vapor while the system is running.
Keep the tank with the closed end of the tank towards the ground, and the valve up towards the sky. Slowly add vapor until the small line coming off the compressor gets about too hot to touch. Also watch the ammeter, stop if the amperage gets to about 80% of the FLA (full load amps).
That's my best advice with what you told me. The big line coming back to the compressor probably will not get cold while the fridge is running.