Thanks for reaching out to us for help. We have a File Upload element that makes it simple for users to attach files when filling out a form. Let me show you how to add it:
Open your form in Form Builder and click on Add Element on the upper-left side of the screen.
Under the Basic tab, scroll down to the Field Upload element and click on it to add it to your form.
You can also specify which File Types your responders can upload. To do that:
Click on the File Upload field, and then click on the Gear icon to open File Upload Properties.
In the menu on the right side of the page click on the Optionstab.
In the File Types section, remove unwanted file types and add the ones you want respondents to upload.