The car keeps overheating. Keep adding coolant, and I don't see a leak.

What is your question?

Also, the temperature gage is stuck in the hot position, All the way to the top, How do I check and see if it is my thermostat that is malfunctioning? I am not even sure where to find it. I keep looking on the internet for that info, and no site will give me the information. Currently I am living in a homeless transitional program, so I cant really afford to take her into a mechanic. Could you please let me know about the thermostat, and any other troubleshooting techniques you may have? Thank you