Propostions are very important in sentence construction. One of the best ways to understand their correct usage is to read books and sentences, and follow the way they have constructed sentences. You should practise constructing similar sentences of your own. For example, start reading an article in newspaper a few days back :
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'Industrialist arrested for fraud' : Understand how 'for' is used.
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Use your own experience to create sentences : Ravi was punished by school 'for' coming late.
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News : ' Viswanathan has to play against Carlsen in the next round'. 'To' is the proposition here.
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In your explerience : I want to go to Disneyland some time.
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I have to write the Olympiad exam next month.
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Of, to, for, with, by, from, till, and such words do a job of linking the subject and the actions or verb. Read many articles for example, newspaper, and try constructing your own sentences.