You may not need to make your code handle batches; it may be enough just to make it schedulable. It depends on how many SOQL queries or DML statements you need to get your work done. Remember, you can get many records with one SOQL query and save many records with one DML statement.
To make a class schedulable, you must either implement the Schedulable interface or call System.scheduleBatch. More details on making Apex schedulable here:
http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_scheduler.htm
Here's a complete batch example that reassigns account owners:
http://developer.force.com/cookbook/recipe/using-batch-apex-to-reassign-account-owners
Here's an example of code that's schedulable and batchable too. It's a little more complex, but if you need to handle more records, you may find it necessary.
http://cloudforce4u.blogspot.com/2013/07/batch-apex-example.html
I hope these examples are useful to you.