First it's important to realize that you only have one "mind" and referring to conscious, subconscious, and unconscious minds as separate entities is not technically correct. It's merely a way to illustrate certain concepts. That said...

Your "conscious mind" consists of whatever you are currently thinking about or consciously aware of. Right now, this post is (hopefully) in your conscious mind.

Your "subconscious mind" consists of things which are not currently in your conscious mind, but can be called into your conscious mind at will. For example, your phone number. What is it? It was in your subconscious mind just a moment ago, but now that you have recalled it and are thinking about it, it is in your conscious mind. Another example is your breathing. Normally you don't think about breathing, you just breathe. At that time it is a process of your subconscious. But you are also capable of making your breathing a conscious process.

Your "unconscious mind" consists of things which are not part of your conscious mind and which cannot be called into your conscious mind at will (but do exist nevertheless). Examples would be a traumatic childhood event that you repress or a distant memory that you can't retrieve no matter how hard you try. Techniques like hypnosis can surface these memories, as can things like a certain scent or familar place, but you cannot uncover things from your unconscious mind purely at will.

The unconscious is often mistakenly referred to as the subconscious.