it comes after
I gave it to Serdar - Onu Serdar'a verdim.
We are going to Italy - İtalya'ya gidiyoruz.
in 1985 - 1985'te
2nd floor - 2'inci kat (i think we usually use 2. instead of this)
to USA - ABD'ye
from a to z - a'dan z'ye
We use it for a few more things but i think these are enough for you for the moment.
Most of the proper nouns take an apostrophe to separate the suffixes. There are a few exceptions though. Most of the proper names which were created from other proper names (such as Türkçede), organisation names and plural suffixes "-ler, -lar" (before them) don't take apostrophe.
However these are very confusing rules even for native speakers. Therefore most people use apostrophe after every proper noun.
And in general; dir,... tir... doesn't matter if you cancelled it when you are speaking, but you are going to write them.
But you must say it when you are speaking when it's mean maybe.
Like, if someone asked you Where is Mohamed? And you don't know, you will say : bilmem, uyuyordur. . and it's mean I don't know, maybe he is sleeping. And if you said uyuyor it's mean ( you are sure) he is sleep. so in this case ( maybe ) you should say it.
That what I know, if someone have something else, addition or comment to this post, i hope to tell us :)))..
Well it's based on "Vowel Harmony" in Turkish. If the final vowel before the suffix is i/e/ü/ö you will put "de" (or te, if the preceding consonant is p ç t k s ş h f). If the final vowel is a/ı/o/u, the suffix will be "da" (or ta, if the consonant preceding is p ç t k s ş h f). eg. TurkiyE'DE...AmerikA'DA.
I hope this helps =)
The ü and the i are chosen due to four way vowel harmony. (See the tips section from the Accusative section. https://www.duolingo.com/skill/tr/Accusative )
The t and d are chosen due to consonant harmony. (I forget which section has tips for this, or maybe I read it in discussion.) Basically you match the voice of the previous consonant. Much like how the s in "dogs" sounds like a z but the s in "cats" sounds like an s. This is because g is voiced, so you voice the s in "dogs" too, but t is not voiced so you don't voice the s in "cats." Except, unlike in English, the spelling is changed to reflect the change in pronunciation.
This all means that "-dir" "-tir" "-dur" "-tur" "-dır" "-tır" "-dür" and "-tür" all mean the same thing. Much like how in English "-s" and "-es" mean the same thing, but are used at different times depending on what comes before them.