If you want to add fields to your template, you can find it under the Add tab.
These fields can be used to merge data into certain parts of your document, be it input fields for the sender or recipient to fill in, or signature fields. To place a field in your doc, simply choose who the field will be connected to, then click and drag the field you'd like to add. Here are three actions you can take once it's on your page:
Click and drag the body of the field to place it where you would like it on the page
Click and drag the corners of the field to resize it
Click the field and then the gear to edit its properties, such as who is taking the action on the field, the label of the text field, or setting a default value for the field
Click and drag around multiple fields to edit them all at once
You can also add supplemental files or URLs to your document to help your recipients make a decision, such as a demo video or terms and agreements, and they will always be attached to the template you have created.