How to execute procedure in APEX SQL script?

I am trying to understand how to use multiple procedures in APEX SQL script. First I don't really need stored procedure, but not sure how to declare simple procedure in APEX SQL script. So this is my attempt:

create or replace procedure test1 as

execute test1;

This gives me an error:

Error at line 7: PLS-00103: Encountered the symbol "EXECUTE"    

So questions - how to create regular/not stored/ procedures in one SQL script and then call them. What is the entry point of execution in APEX SQL script?