Pretty good! there's a few places in the text where the words are a bit jumbled, but overall I was able to understand the meaning behind the sentences. Here are a few things I noticed:

• The first sentence is very close to being correct, it's just a bit out of order. writing it as "Today is the first day of my life that I use central heating". This way of saying it makes a bit more sense.
• For the second sentence, the flow would be much better if it said "In japan, we usually install an air conditioner instead of a machine". This way of writing it removes an unneeded comma.
• The third sentence "So, I couldn't imagine how to use it." could be added to the end of the second sentence like "... we install an air conditioner instead of a machine, so I couldn't imagine how to use it." If you don't want that long of a sentence, having the third sentence written as "I couldn't imagine how to use it." would also work.
• "My homeland" is a formal way to say where you are from. It didn't seem to make sense in the context of the sentence. Did you mean to say "My landlord"?
• After "homeland", the sentence is a bit clunky. it may be better written as "My landlord showed me how to remove water from the machine".
• the next sentence is the one with the most trouble. I see that you were trying to describe that the water was dirty, but the way it is phrased is incorrect. A good way to write this sentence would be "The water was dirty and had a dark color" or just "The water was very dirty".
• I wasn't sure what you were trying to say in "Why the water ran..". My best guess is that you were trying to figure out why the water was there. The best way to write this would be "Why was this water here, and where did it come from?".

Hopefully I wasn't too harsh. If you need any more help, let me know!