Move all running VMs to the host you are not going to update
Click on the datacenter (bps-1221 in MSU's case) and then select the OpenManage Integration tab. Click the update firmware button, then select Next three times.
Select the updates on host you want to update, then select next until the last screen.
Choose Update Now and click Finish.
The update should take about 30-60 minutes. When it is done the host should automatically be reconnected to the vCenter.