If you prefer to set your own default image dimensions, you can do so from the Media Settings menu. This short tutorial walks you through the process.
The WordPress.com dashboard is easy to set-up, customize and use the way you want to. This video walks you through it’s features
This short video introduces you to adding and managing widgets on your WordPress.com blog.
Adding links to your blogroll doesn’t do anything for your readers unless you display them on your blog. So make sure to add the Links Widget.