Try to find online audio recordings of native speakers saying the dates. If you have a language partner, ask them to say the dates and you can record them. Then, practice saying them with the recording. Also, it's spelled "twelfth". We normally just write 12th though. British and Americans say dates a little differently too, sometimes. American: "June seventeenth" is normal but sometimes we say "the seventeenth of June". British: Always say "the seventeenth of June" If someone asks you "What is today's date?", you can respond with "Today is the twenty-first".

Hello I think you mean to How to speak about dates and ordinal numbers? I think th is quite a hard sound to master and only comes by practising them. Why not speak to someone on Skype, a language partner? Here are some links that can help maybe http://www.real-english.com/reo/8-b/unit8b.asp http://www.talkenglish.com/LessonDetails.aspx?ALID=388 http://www.esolcourses.com/content/topicsmenu/numeracy.html

It sounds as if you still need to practice the "th" sound. Make sure you're saying it right (there are plenty of youtube videos on "th pronunciation" if you can't find a person to show you), then practice moving between sounds. Remember that in English, some consonants are pushed together without vowels, so you can say those sounds quite heavily. You don't need the light and short endings you use in bahasa indonesia. For fifth and twelfth, practise the "fff-thhh" transition. For eighteenth (or any of the teens), practise the "nnn-thhh" transition. Native speakers even find "sixth" difficult, so practise that as well: "ik-sss-thhh"