How to customize the registration page?

I already searched in the forum, but could not find how to customize the registration page in a way like the Joomlapolis site. There are more TEXT DESCRIPTIONS for the fields, see for example the SUBSCRIPTION PLAN form.

How can I insert that kind of description texts in the registration page?

Another question: after the user is loged, in his PROFILE PAGE, in the EDIT PROFILE PAGE, I see many fields more than in the REGISTER page form.

How can I turn off the fields that show up in the edit profile page?

The subscription plans is something CBSubs adds (see CBSubs tab above for more info).

You can also add more description text in registration form either populating the Introduction text and Conclusion text parameters in the CB backend Configuration -> Registration Tab area.

You can also use delimiter fields to do this.

A CB field can be marked to show (or not show during registration).

All of this is described in the detailed documentation available to CB Documentation subscribers (along with many CB Team released add-ons) - sounds like you would benefit from this.