Keep the questions coming.
Yes, it's very easy to get all the cases of words once you know what you're doing.
Think of how words in English ending in "ium" become "ia": stadium -> stadia, and how "ius" -> "ii": radius -> radii. Well that's how it works in Gaeilge, ie. there's special endings.
Here's the special endings:
(or any other vowel other than í
Go to An Foclóir Beag
and type one of those words in and it'll show you all the cases.
Outside of those, you work with the last vowel.
They all end with broad vowels, and as such, they're all masculine and worked with as so:
lár an phobail
lár na bpobal
And then you have slender vowels:
they're all feminine and they're worked with as so:
ionad na béime
ionaid na mbéimeanna
And outside of that, you just have plain old odd ones:
timpeall na tine
(You would think that tine
is masculine, it ends in a vowel, but it ain't)
ainm mo charad ( cara becomes carad, no explanation!)
an t-ainm -> na hainmneacha
an oíche -> na hoícheanta
(not an exhaustive list)