SQL & PL/SQL

I want to get a handle on the col width of ALL the tables owned by a user.
I have this syntax to check individual tables:
SELECT COUNT(*)
FROM user_tab_columns
WHERE table_name = <tbl_name>;

But, I did a DESC on the USER_TAB_COLUMNS and there isn't an owner\user that I can use to get all tbls.

Any suggestions how I can get this to go thru all the tables ( i'll spool the output to a file)