Tool to create ERD
Here is an online tool ERDPlus (note: The link has been fixed if you could not open the site earlier. 09-05-2013) you can use to create ERD for your assignment and exercise. You can follow its Youtube tutorial “Creating an Entity Relationship Diagram.” to get familiar with the tool.
However, before you start to use this online tool, I encourage you to practice drawing ERD by hand until you get comfortable on how to specify the cardinality. Hand drawing helps you to think through the rationale behind the denoting. The key is to specify only one direction at a time: along the direction, first specify at least then specify at most; then you do the same thing for the reverse direction.