If you don't feel confident performing actions via shell, you can perform such updates/upgrades via WHM.
WHM >> Software >> Apache Update
This will let you update Apache and PHP.
Ensure that you always select "Load Previous Config" and, to make things a bit quicker, check "Skip Apache Build if up to date". You can select the version of PHP you would like to use and select from a range of modules to include in the build.
This will also update Apache to the latest version available to the update tree you're using.
WHM >> Software >> Update Server Software
This will update to the latest WHM/cPanel as per the update tree you have selected. 10.8.1-S114 is the latest STABLE release at the moment, so there's no need to upgrade just now.
You should check
http://layer2.cpanel.net/ for details of the latest versions in each release tree.
If you want to use a different release tree, go to WHM >> Server Configuration >> Update Config and select whatever you'd like to use.
WHM >> Software >> Update System Software
This will run your OS updater, which may be yum or up2date for a RH-based machine. The daily run of /scripts/upcp should take care of most OS updates, although this depends on your update config.
If you feel confident in doing the same through shell, running /scripts/upcp will update WHM/cPanel and your OS and /scripts/easyapache is the shell-based equivalent of WHM's Apache and PHP builder. Use /scripts/upcp --force to force a reinstall of WHM/cPanel.