Hi.
I suggest that if you want to start a career in networking, you may want to take a class on it, purchase and study books, use online reference materials, and/or use online virtual training.
When it comes to certification, you can either start with the beginning level of certification from Microsoft Learning. The MTA certification exams test your skills at an entry level. here is the MTA exam on Networking:
http://www.microsoft.com/learning/en-us/exam-98-366.aspx
Microsoft offers free virtual training at Microsoft Virtual Academy. This course will get you started:
http://www.microsoftvirtualacademy.com/training-courses/networking-fundamentals
Alternately, you may prefer to earn your MCSA and eventual MCSE in Windows Client/Server Infrastructure. These certification exam titles require you to pass a number of exams to earn them. Note that exams passed for MCSA count towards the superior MCSE title.
MCSA:
http://www.microsoft.com/learning/en-us/mcsa-certification.aspx
MCSE:
http://www.microsoft.com/learning/en-us/mcse-certification.aspx
When you are ready to take an exam, you must register at the online Prometric site:
http://www.prometric.com
Good luck!
Best wishes, Davin Mickelson