programming using system calls

[nisa]

hi,
i am quite new to programming using system calls and would like a basic idea regarding the usage of system calls.
i would like assistance in the following area of c programming in linux:
1.how to open a text file ,read data and print the data on console using system calls
2.create a text file and write some data
3.read data from a file and append that data to another file using lseek()
4.creation of a parent and child process using fork()