Different databases treat truncation and wildcard symbols in different ways. To check what symbols you should use in a particular database, check the help pages. Open the document above for some common examples of truncation and wildcard symbols.
If you want to see a more comprehensive list of databases, please see the Databases A-Z list which you can filter by subject.
The videos above should help you develop an effective search strategy to identify journal articles for your first assignment. You should see the Library Skills guide for very useful demonstrations on Searching the Library Catalogue and Searching the Library Databases.