install worpress si-contact-form using wordpress login/password

from
https://www.experts-exchange.com/questions/28406128/wordpress-text-area-contact-me.html


I use this: https://wordpress.org/plugins/si-contact-form/

Very easy to configure, can create a contact form in minutes. Add this to your contact page:
[si-contact-form form='1']

PS: make sure you're protecting it with Captcha or similar, or you will receive spam.


wordpress 3.7. Hosting is godaddy (shared), client has low budget so all I can do is a contact form.  client will not pay me for wordpress update or moving away from godaddy

How do I add this plugin to website.
All I have is wordpress username and password

do I need to ask for ftp (would be easier if I could just do this in wordpress)