If you want to create/insert you own question into to form, you can do so by Adding New Custom Question.
You can find the option at the left panel under Design >> Forms
To create New Custom Question:
i. Click on the Create New Custom Question under Custom Question at the right panel
ii. Type question name
iii. Select from dropdown type of question
iv. Once you're done, click Save
v. To add the Custom Question into your Form,