Ron,
Thanks for posting the picture. It would be nice if you answered some of my questions so I can assess the level of your knowledge. It OK to be humble and play the fool but if you keep doing that you will get treated like a fool.
Your picture is of a different model of the STC 1000 than the one used in Post #65. The model you have is wired like this one:
He is wiring it for 110 Volt AC operation so if you are going to use it with 12 V DC or something else you will need to wire it differently. I don't know if you know how to use a volt meter. I don't know if you know how to solder. I don't know if you will understand my explanation.
The two models of this controller are similar to other brands of controllers like the RANCO that I have. One model, usually slightly cheaper, has only one relay, which switches the power to the device you are controlling. It can be programmed to Heat or Cool, which means it switches the power ON when the temperature probe senses a temperature BELOW the set point when heating or, alternatively, to cool when the temperature when the temperature is ABOVE the set point.
Your STC 1000 appears to be the more deluxe model which has two relay switches, one will be ON (closed) when the relay is BELOW the desired temperature, and the other will be ON when it is ABOVE. The combination is needed in a process like brewing or incubating live animals where there is more than one source of heat and sometimes you cannot electrically switch the heat off so you also need cooling. If you are not going to cool your plants you only need to use the Heat relay connectors.
I'm also going to caution you that I don't know the rating of the STC 1000. People on YouTube are using them to control small heaters and coolers so it looks like it will work for your application. They are using 110 V, so the amperage is lower than it would be if they were directly switching 12 volts (like the car headlights).
If you want to control your Westinghouse washing machine pump with this controller you probably could, but Westinghouse makes hundreds of models and unless you supply a model number or part number it will be hard for anyone, even an expert, to tell you if it will work for sure.
The $5 heating pad I found for you is made to glue onto plate glass at the bottom of 3D printers. It will get hot enough to melt plastic and you will need to provide a power adapter big enough. A power supply for a printer or computer is about the right size. You will also need to solder the wires to the pad. If you don't know how to solder you will need to learn or buy a pad that has the power wires already connected.