how can i get, if i have 64mb, 128mb nand?

i bought a mini2440 but i cant get all the information

If your  board is loaded with linux , from the terminal give the command
cat /proc/cpuinfo .

Analize installed chip or just flip the board: mine have a sticker with the
nand capacity.
F.

Read the numbers off the flash chips and go to the downloads page for the
datasheet.