Half the battle is knowing which tool to use. In order to import data from Excel into your database through Oracle Forms, you need to use the WebUtil library. Oracle Forms 10g comes with the library, but you need to download and configure the Java Com Bridge (JACOB.jar) Java archive/library. Search the Oracle Forms Help system on Configuring Webutil. This will give you three results. Print off the Runtime Setup Checklist and Configuring WebUtil topics and follow the checklist as you are reading the Configuring WebUtil topic. Make sure you complete each configuration step.
Once configured, search the Forum for "Import Excel using WebUtil" and you will find numerous threads on this subject.
first step should be to make sure what kind of file it really is. Sometimes a simple CSV file is called an Excel file while it could be handled more simply when it is treated as a simple text file. When it is an Excel file, then it can make a difference whether it is an XLS or an XLSX format.
As long as you use OLE functionality it will make no difference, yet when you have to handle it without Excel installed it will make a diference between simple and almost impossible.