If you’re talking about the GITIS entrance exam, the best thing is to practice recognizing main points and supporting points. Writing traditional outlines in indented form is a good way to practice. You can also practice by watching brief news items, for example, and just telling someone what they said in 2-3 sentences, being careful to get the main points and leave out the “fancy stuff”.
Judging from what you’ve written (just in one short post here), however, I’d work on my English as well. The entrance standard for English is very high, and you’ve got misspellings and non-native usages (“I’ll have a test” should be “I will take a test”, for instance). I’m not trying to flame you, but if this is the test you’re trying to prepare for, it’s better to know in advance so you will know what to work on, right? You need to get away from “Taiwan-style English” as much as possible. It’s one of the main reasons otherwise qualified students either don’t get admitted, or are not allowed to continue with the program. (But maybe I’m guessing entirely wrongly and you are actually applying to another program.)
In any event, good luck!!