adjective with article

Hi, i begin to work on the lessons few weeks ago, and now i'm on the
lesson 5. But I would limke to know how to use adjective with
definite nouns. For example, we say "Konungr er illr" for "a king
is evil", but how we say "The king is evil" ?????? In the lessons,
for now, we have :

indef.
nom. +r +ir
acc. +an +a
dat. +um +um

but what is the part for definite??

thank for your help