Read only to schema

Hi Guys,

Yesterday i tried all day to figure out system to read only schemas.

I want to :

1. Create user who can login (user: jaryszek)
2. Create role who can read only data (only watching tables) (role:
readonly)
3, Create role who can read all data (inserting, deleting, altering,
dropping) (role: readall)

What sqls should i use for this?
What grants should i add?

And now i am logged as jaryszek

I want to grant myself role read only to schema public (when owner is
postgres).
I want to review tables as views only,
After work i want to grant myself role readall to schema public.

It is possible?
Or possible workaround ?

Best,
Jacek