How can I add a form to a holder theme

Hi. I create a coming soon home.
Now i want to add there a contact form.
How can i do it?
It says also that i can add a blog to the holder. But then i how i put it.
And last one, how do i change the text size?
Then i have to keep working in my design for in a page named different, and at the end delete the holder. is that right?
Thanksss