I found this video that shows you have to create a database when ASM is installed.
I found that when I manually created the Oracle Database, that because the ASM dynamically names everything, I simply removed the directory & file name reference and replaced it with the +ASM group where I wanted the datafile to be located. If you look at the ptddl script for a PeopleTools database or the hcddl script for an HR database you will see how it will say the directory+file name:
‘/oracle/oradata/dbfiles/tablespace1.dbf’ is replaced with:
‘+ASMHRORPTGROUP1’ depending on what you named it.