Custom Button in User Form

Hello Everyone.,

I would like to create custom buttons in user form and disable the save and complete buttons.Instead I would like to embed the complete button functionality to my button click.I am using plain html to create user task.I am not using angular.

I would like to associate cam-variable-name with this and set its value on button click and complete my task.
Is there any way for this?Please let me know.

Gayathri S.

Can anyone help me here?
Thanks in advance.