To add a Dynamic Email Content first we need to create the block going to Asses > Dynamic Content:
Click on New Dynamic Email Content
Then select the Email Dynamic Content Templates, add a name for the dynamic block and select Create
Here you are able to edit your block with the content and structure as needed. In this case we are adding a simple text which will also be the default (no advanced targeting)
Now we will create an Alt. Version and add the name of the version, we will select the current email content as the base version, then we will hit Proceed.
After editing the content for the second version we can set the query, in this example, we want the text of the second version to show to contacts with a Gmail account.
Once we finish our query we can save the dynamic block and go to our email we are building, and select the Dynamic Content and drag and drop our Dynamic Block just created
Then you will have your Dynamic block added to the email and it will change according to the query selected!