On the top, there are the buttons switching the view and letting you preview or publish your work so far (check this github pages tutorial). The brush over it is the Style changer – play with it to switch essential options or see an entire site with new colors or fonts. All the blocks you need are on your right side panel which you can call with the Plus button. The most important rule to follow starting up with web design software is – Remember to have Fun with it! Do as it says and great the great results will come out on their own.
