By the default, the url for category and pictures are like following:

http://www.example.com/piwigo/index.php?/category/1
http://www.example.com/piwigo/picture.php?/1/category/1

now i want to change that  pattern to this:

http://www.example.com/piwigo/category name
http://www.example.com/piwigo/categoryname/picturename or tagname

what configurations that i need to set?