compiling linux file system

hi

i have a board and i want to compile linux file system and download it on board but i dont
know how i can compile the file system if you have knowledge about this matter please help me

Well mentioning which board and which file system would be a start.

Also, what sort of "file system devices" does the target have - disk, flash etc.

As would mentioning what your current setup is for your host development, and how much further than "hello world" you've got in downloading other types of programs to your target.