Antimatter Vs Matter.

How does it work ? , what is it made of ? Etc. Could there be antimatter galaxies ?

Antimatter consists of particles identical to matter, but with opposite charges. Anti-protons, for example, are identical to protons in most properties, but have a negative charge. Anti-electrons, or positrons, are identical to electrons, but have a positive charge.

Antimatter is no longer theoretical. The discovery of the positron established its existence, and since then, many forms of antimatter have been found. A particular type of particle, the meson, consists of a quark and an antiquark (a subatomic particle of matter, and one of antimatter). Matter and antimatter annihilate each other on contact, releasing energy. We are not sure why the Universe is made up of matter and not antimatter, but hypotheses abound on this subject.

Antimatter and matter are both made of sub atomic particles and at a deeper level possibly strings. Yes there could be antimatter galaxies just like there are matter galaxies. I do not have sufficient understanding of the subject to explain how matter "works". I am not even sure what that part of your question is asking.

We don't really understand antimatter yet. At the moment it is only a theoretical concept.