First, ensure that you have selected the correct client you are trying to create/add a new tax form. In the example below, the name of client selected is "Doe, Banana" (the type of forms available for selection will depend on the Entity Type of the client). To manually create a tax form, just click "Add form" and then select the type of form in the dropdown list. 

Click "Individual Tax Return" option to create the individual tax return form.

Select the "Year" and click "Create & Prefill".

Click "Continue", if you don't need to import financials. (You can also import the financials later on, once you have created the tax form.)

Select the applicable Sections and click Continue.

Note: You can also add the Sections via the 4 square icon in the upper right side of the form, after you had created the tax form. See below image:

You have now successfully created a tax form (individual tax form as per image below):