Hello Jeffrey,
First, and most importantly, congratulations on your internship! Yea!
In an attempt to answer your question...Here in the United States I always began with the annual report filed with regulators. Here in the US this is known as the 10-K. Unfortunately, I am not familiar with the equivalent document in Indonesia. But this document in the US has a description of the business, a thorough listing of business risks (drafted by a company's paranoid legal team!), a discussion of competition, a review of the last several years of performance, the financial statements, and the footnotes to the financial statements. I am guessing that massive and important Indonesia must have an equivalent document. After the 10-K I would look for any industry trade associations created by the industry as they frequently issue white papers and provide public comment on issues important to the industry. Because you are young in your career it may also serve you to look at the research reports issued by sell side firms that cover the cement industry in Indonesia. However, after my first year as a research analyst I stopped using sell-side research reports completely because I saw them as biased and a bit lazy.
Again congratulations, and best wishes for success!
Jason