Cannot install plugins, custom themes or third party themes on sites hosted by wordpress.com. Got it.
But if you need their forum, then open this link. , then you are mistaken/misinformed. We have never had that ability. You are confusing wordpress.COM hosted blogs and wordpress.ORG installs on paid hosting.
Blogger installed plugin capability does not exist on WordPress.COM blogs and there is no upgrade you can purchase here that changes that reality. Permalink structure cannot be changed on sites hosted by wordpress.com
For that type of functionality, you’d need a self-hosted WordPress.ORG software install running on a paid web hosting service.
See: Moving to Self-Hosted WordPress
WordPress.COM and WordPress.ORG are completely separate and have different username accounts, logins, features, run different versions of some themes with the same names, and have separate support documentation and separate support forums. Read the differences here http://en.support.wordpress.com/com-vs-org/
If you don’t have a username account at WordPress.ORG account, then click http://wordpress.org/support/ and register one on the top right-hand corner of the page that opens, https://wordpress.org/support/register.php so you can post to the support forums there.
Resetting your WordPress.ORG password http://codex.wordpress.org/Resetting_Your_Password
WordPress.org support docs are at https://codex.wordpress.org/Main_Page
See also https://apps.wordpress.org/support/
1. Buy Now button.
Here is a step-by-step guide on PayPal.
One more example on how to get the PayPal button code
Video tutorial for get the PayPal button code