To find out if you're using Shopify 1.0 or 2.0, you can check your theme's settings:
Go to Online Store > Themes in your Shopify admin
Find the theme you want to edit and click Customise
Select Products > Default product
Look in the sidebar for an Add section button below the section list
If you see the Add section button, you're using Shopify 2.0
If you don't see the Add section button, you might have a vintage sectioned or non-sectioned theme. This is most likely Shopify 1.0