It is okay to start looking for information using Google (or internet search engine of your choice). However, using Google Scholar can help you target more scholarly information. An added benefit to using Google Scholar is that it provides links to full text articles provided by the Purdue Libraries.
If you are off campus, you can edit the Library Links in Scholar Preferences so Google Scholar will continue to highlight the full text that is available through the Purdue Libraries.
If you are expected to do a comprehensive literature search, you should consider using some of the scholarly databases provided by the Purdue Libraries.