Here are some easy steps to help guide you:
1- Think about your campaigns purpose. Do you want to give readers your website or contact details, share promotions, weekly digest, etc
2- Using the purpose of your campaign, what are the recurring sections? Quote of week, new inventory, new promotion, etc
3- Write the contents of each section. Keep in mind that the shorter and clearer the texts are, the better it is for conversion
4- Round up your brand logo, colors, etc. This way, you can setup the template the right way from the start.
5- Click on add block and start adding the block types in order one after the other.
6- Copy paste your texts and upload your images. Et voila !
You are ready to send yourself a test and send your campaign.