Oracle Form Builder Help!! Importing excel files to oracle

Hi there! I am currently doing a project on importing text files and excel files to an oracle database and my front end is in Oracle Form Builder. I am not much familiar in PL/SQL, but I'm working on it..I used to convert first excel to csv files so i can manipulate them easily..I am using the text_io package in oracle to read them..My problem is that i don't know how would i insert those in the tables.. I used exec_sql package on this, unfortunately nothing happens.. I don't know which of those built-ins would come first.... Could you help me out on this? thanks in advance!