focusing to a career path

im an an electronics and communication engineer.. im working now in a telecom company, i just want to ask if i choose to become a network administrator , what shuold be the starting point of this career? what should i need to learn or to study? i was a bit confuse…i dont know what topic should i study first, i had some idea but i think it whould’nt be enought so thats why im trying to as some sugestions.. thank you for the help you would give…