First, save your visual by clicking on the Save button at the top right. You will be prompted to enter a title for your visual, press return, and it might take a few seconds while a thumbnail is generated. After this, your visual will be saved in your account (found in dashboard) for future use.
Next, click the Download option in the upper right. A popup will appear. Here, you can pick the type of download (image/ PDF), size, and resolution (Original/ Medium/ High Resolution/ Custom) for your download.
You can also choose to download your visual as blocks (Zip file).
If this download doesn't happen automatically, you can right-click on the thumbnail and choose where on your computer you would want to save your visual.
Happy Piktocharting! :)