Sorry for the English.
A good data sheet (English) on the PCF8563 can be found here -> http://www.nxp.com/acrobat_download/...PCF8563-04.pdf
One thing to remember is that the PCF8563’s data is in Binary Coded Decimal (BCD), here is a link (German) about that -> https://www.roboternetz.de/wissen/index.php/BCD
I also found a tutorial link (German) about the I2C Bus -> https://www.roboternetz.de/wissen/index.php/I2C
I hope this gets you started.