To install SNMP on Windows 7, open the Control Panel and click on Programs and Features. Next, click on Turn Windows features on or off and wait for the dialogue panel to be populated. Once populated, scroll down and check Simple Network Management Protocol (SNMP) - there should now be a tick in the box - and then click OK. If prompted by a UAC popup at any stage, provide the requisite credentials to continue. Note that the service might take some time to install. If it prompts to restart your computer, then restart it.
The following section is optional:
After installing SNMP, click on Start Orb and then type Services.msc in the Search box and hit Enter. Next, scroll down in the right pane and right click on SNMP Services and select Properties. Next, click on the Traps tab. Now, in the Community Name box, type the community name to which your computer will send trap messages and click on the Add to list button. Finally, click on OK and then close any open dialogue panels. It might be a good idea to restart your computer at this point, even if it doesn't prompt you to.