SNMP API C#

Question

hi
I new in snmp issue. I got a new Job to monitor devices and application using SNMP method.
I have to use only free & open source code.

As a NMS I think to use MIB Browser. ( any other good suggestion)
I have a "hello world" console application.
I want to attach my application a snmp agent + MIB ( how I write MIB for custom application?)
For my first step I just whant to know if the process alive? ( ="hello world" application)

Please lead me in small steps how to do that?
I'll appriciate if you can write me down the code/ dlls I have to use.
Thanks alot
sahar