Ethernet + MDUINO 58

Hi Guys

I'm involved in a project that consist in read a UDP frame from Pc to Arduino MDUINO 58 ( for industrial purposes)
I have an application which send udp frames to Arduino, but I don't know how construct de communication link between IP's and Ports.

I have problems with libraries, the M duino 58 uses Ethercard library. If I reach communication between Pc and Arduino I can work about the algorythm.

If and expert can replie my or chat, i'll be so grateful!!