just flash the zip file. I'm not responsible if anything happen to ur device, but diz is how i usually do it.
Since ur new to flashing. U have twrp installed right?
1) If u are on 4.4.3 (KTU84L) and u wanna update to 4.4.4 (KTU84P), just download the link for KTU84P from KTU84L. Remember to download the correct 1, since there is 2 version, nakasi or nakasig.
2) put the zip file that u've downloaded into ur Nexus 7. Rmb the directory where u put it.
3) boot into recovery, twrp in ur case.
4) tap 'Install', find the zip file that u've put in ur Nexus 7. Rmb the directory where u put it just now?
5) swipe to confirm flash
6) wait for it to flash, after flashing, choose reboot.
7) updated to 4.4.4
the steps above ONLY works if
1) u are running on 4.4.3 and u wanna update to 4.4.4
2) u are using twrp as custom recovery
3) u downloaded for the right version, wifi or 3g

not much noticeable changes. based on google, they juz wanna fix some security issues.