Case in a select statement

I'm not that familiar with case statements.  I am trying to do something like the below select, is that possible?  I keep getting the following errors:, what am I doing wrong or what am I missing?

Error report:
ORA-06550: line 21, column 27:
PL/SQL: ORA-00905: missing keyword
ORA-06550: line 4, column 2:
PL/SQL: SQL Statement ignored
06550. 00000 -  "line %s, column %s:\n%s"
*Cause:    Usually a PL/SQL compilation error.
*Action:

Here is the Select:

declare
v_transfer_inst varchar2(4);
begin
 select shrtrce_pidm,
          spriden_id id,
          shrtrce_term_code_eff,
          substr(scbsupp_cudb_code,1,2) aid_code,
         shrtrce_subj_code||shrtrce_crse_numb offering,