First, create either an embedded form or a popup form via the SEMSblast control panel.
When you have finished designing your form you will see a piece of code you can copy. Highlight and copy this code.
Now login to your Shopify account and edit your website.
Click on the ONLINE STORE icon on the left, and then select THEMES
Click on the little box with the three full stops in it located at the top right, and then click the EDIT HTML/CSS option that appears.
Now click on "theme.liquid" under the LAYOUT section...
In the code window that appears on the right, scroll down until you see the section of code starting .
You can insert the SEMSblast Form Code you copied in Step 1 of this guide anywhere into this area. We recommend replacing the code we've highlighted in the screenshot above.