Adding a Terms & Conditions portion to your form is easy and can be accomplished by adding a Long Answer field to your form. Make sure to set the field to "Read-Only" and enter the Terms text into the field. The user will be able to scroll down and read the full text. Then, add a check box field with an option that says "I agree to these Terms", etc. You will also want to set this field "Required" to ensure the user agrees before they can submit the form.
If you would like to use a PDF for the terms and conditions, you will need to use an Embed Code or Description Area field to add a link to the PDF on the form.