> Does anybody know where to find a whole description
> about the page size parameter for the database
> creation.

Whole description of what page size is:
"Page size parameter specifies size of database page." :-)

Whole description of what database page is is here:
http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_expert2

> What does 2048, 16K page size mean?

In short, you can choose from those sizes
1k, 2k, 4k, 8k, 16k
(i.e. 1024, 2048, 4196, 8192 or 16384).
For most cases 4k or 8k are the best (choose whichever one.
You can make some tests, but I do not think you will observer
much difference)
There is no real reason to use 1k or 2k.
Before using 16k, better make some tests (for me 4k and 8k
were equally good, while 16k was a bit worse, and 1k/2k were
the worst in performance)

Once the database is created, its page size can't be changed,
but you can make backup, and when creating new database
from that backup you can specify new page size, so testing
different page sizes is easy.

Ivan