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 Weebly account and edit your website.
Click on the EMBED CODE tool at the top left of the page and drag it onto your site where you would like your email signup form to appear.
Click on the new Embed Code area you just dragged onto the site (where it says "Click to set custom HTML").
In the tool bar that appear, click the EDIT CUSTOM HTML button.
Paste the code you copied in step 2 into the box and then click anywhere outside of the box to save the changes.
You now have an email signup form on your Weebly site and are ready to start collecting subscribers and doing some email marketing!