sending data over UDP from serial port

hi all,
i am new to this forum and also new to linux programing.if i undertake any steps or follow things not to be done here i wud appreciate your view.

i need help on a program. i have 5 serial ports in a PC. i have to write a program to send data over 4 serial ports to 4 different computers. these computers to which i have to send data do not have serial ports to recieve data. so i am using ethernet to serial converters. IP of the converters been configured.
now i need to write a program in C, which sends data through 4 serial ports in my PC to the 4 computers connected with the specified IP( of the convereters)

making my issue clear it would be like
1. data from one PC goes out through serial port.
2. data has to be sent to a specified IP, not to a serial port.

how can i go ahead on writing a program for it???

thank you...