i own and have configured a c2950-24 L2 switch. upon starting it up it asked if i wanted to configure snmp. i followed threw some steps but i have no clue how to actually use snmp. my switch logs when an Fa port is up or down and that's it. i also have freeNas which has snmp on it. do i make the server control the switchs' protocol or something how does that who interface and communication work, as well as setting up traps on the switch with FreeNas. i'm at a complete lose.
but I have no clue how to actually use snmp
For the devices you describe, you can safely ignore SNMP. You would normally use it to monitor the performance of network devices (and others), but with just a couple of devices, there's little point.
If you're really interested, there are lots of resources on the web to learn about snmp. you should know it's slowly being replaced by NETCONF/Yang.
Like the previous answer says, SNMP is mainly used for monitoring the condition of the switch or the NAS (or some other device). Different devices supporting snmp will have an agent program installed that standardizes information about the device and its current settings/ status into an SNMP compliant format.
Then using an SNMP client such as a network monitor,you can inspect all the different data about the device (reading), and depending on the specifics, make changes to the device using SNMP (writing).
The exact specifics of how this happens have some differences across devices and SNMP protocols, thought the core functionality of SNMP is consistent overall.
Here's a quick video that gives a bit more clarity and context!