No problem, I requested to add you and if you have anymore questions feel free to bug me personally or ask on the forums, I know a lot of people on here love to help too!
"Apps" are Applications. It's what you submit when you 'apply' to join a guild. Sometimes, certain guilds require you to fill out ones on their own guild websites outside of Mabinogi, other times you can just directly put a request in at the guild stone -- maybe note the guild leader or officer to let them know you are interested in joining.
It's so awesome that you have so many questions. It's great to hear that you are really trying to understand the game! The next time I log in to my Alexina character I'll send you an add request, and let you know it's me from the forums Is your IGN the same as your forum name? Also, don't be afraid to click on guild stones to read over them, it's best to always do that first anyway to make sure that the guilds are actually recruiting and accepting membership . Some guilds even request that you do apps on their own guild websites before applying from their stone.