Using a plugin to install a conference registration button

PLEASE HELP. I am responsible for a non profit’s website and am learning as I go. I have a registration form for a conference from planetreg.com
however the site says that word press will mangle the code (I don’t know code) so that when I cut and paste the code into the page, it doesn’t convert to a reg. button. It just publishes as the code. SO, planetreg suggested installing a plugin so it will work properly. I have installed these two: Better wpautop and Event Registration

So, once I have a plugin installed (now you will see how little I know about what I’m doing), how the heck does it work to make the button code turn into a button? Is the code now supposed to magically turn into a button because the plugin is installed? OR do I need to do something WITH the plug-in on the page I’m editing to make this happen.

Please advise and use VERY basic language and please assume very little knowledge on my part. I am probably not as bad as I think. But I appreciate this community of experts immensely!