Saying years in English should be simple, but interference from Slovak can make things tricky. First separate the number mentally into two halves, and then say them as simple numbers, so 1989 comes out as "nineteen - eightynine", 1776 is "seventeen - seventysix", and 1900 is "nineteen - hundred". It's important to say the "-teen" clearly. There are no "firsts" or "sevenths", and don't say the word "year", because everybody should recognize that you're saying a year in this way.

For whole decades, say the first year and add /z/, like "in the nineteen - sixties", and forget about "the sixtieth years of the twentieth century". Just now the situation is interesting, because the new millennium started with the year "two thousand" (not "twenty - hiundred"), because that's what it looked like. Now we're in "two thousand nine" (it doesn't look like "twenty - oh - nine"), but I predict that people will start saying "twenty - ten" next year.