After you launch the software, you should see a 'Quick Guide' tab to the right.
Within here there are step-by-step instructions to create your first design and get familiarised with the basic functionality.
Under Help/Resources, you can find direct links to video tutorials and quick reference cards if you are using a touch based PC.
Please also see:
Quick Video Tutorials- https://designspark.zendesk.com/hc/en-us/sections/202625729
'First steps' series - https://designspark.zendesk.com/hc/en-us/sections/202853505