The problem is in PL/SQL. I'm new to SQL and I can't get the script to run. How to fix?

Question

SQL

Hello everyone, I am new to SQL and my script is not running. What needs to be fixed?
if vErr = 0
then
if( select * from qdg q
where q.iqd in (2,3)
and q.iqdg = 0)
then
CLOSE(r,
c,DOC,D,N,G,P, PC );
else
ACC1.Change(
p_acc => P,
p_cur=> vC,
p_pr => '3',
p_b => 'By order of IS system ID=' || DOC,
p_err => vErr )

Throws this error for if and else