If you like to use Visual Studio to create workflow in SharePoint2013, here are the steps on how to get started.

1. Create a SharePoint sandbox solution.

2. Add a list workflow

3. I add a WriteToHistory to the workflow.

4. Here is the final solution looks like:

5. Deploy the sandbox solution to your Office 365 Preview and activate the site collection feature first

6. Then you can activate the site features in the following orders

7. You can run your work as shown below

8. Navigate to your workflow history list, you will see the workflow is successfully completed.

You can download the solution here.