Read only to schema

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