The first thing you could do is change the image

(I think they recommend 960 pixel wide x 275 high, but you can experiment)

then you can go to Plugins on dashboard left and configure Akismet, which will require a free Akismet account

then you could configure Jetpack which will require you to create a WordPress account

then could play around with all the Appearance and Settings menus

To do these things and explore WordPress in general, click on top left menu

have fun

Here are a couple of videos about WordPress,
which I found. I’m sure you could find more

http://www.solostream.com/blog/tutorials/video-introduction-to-wordpress/

And there’s also this: