Can I use it just like RS 232?
You can use 485 like 232 but not the other way around.
RS-232 is not suitable for a multi-drop bus because you cannot disable the transmitters. That's why RS-485 is popular because the transmitters can be tri-stated to allow others to talk.
Is there any good tutorial on RS 485?
I haven't looked in the last 20 years so don't really know but did a bit of Googlinghttp://www.lammertbies.nl/comm/info/RS-485.htmlhttp://www.radio-electronics.com/info/telecommunications_networks/rs485/rs-485-tutorial-basics.phphttp://www.bb-europe.com/tech_articles/rs485_basics.asphttp://www.bb-elec.com/tech_articles/rs422_485_app_note/table_of_contents.asp
I'm not sure these are good
but they should give you the idea.
How does Slave to Master works?
Basically the master asks a slave for information or sends it a command, and the slave provides the information or actions the command.
Usually this is done by sending a "packet" to the bus, this packet has control information such as slave address, data length and a checksum. The slave responds either with data or just an acknowledge so the master knows the data/command was received. The master then moves on to the next slave address and the process repeats until all slaves have had a go. Then the master goes back to the first slave etc etc.
This is called a "protocol" and there are a 1000 variations. AFAIK no (simple) standard exists so you have to write your own protocol. Writing a robust protocol is not a simple job, however something quick and dirty is easily achievable. As this is for a model railway nobody will die if some data is corrupted, that always helps