Please Help ...new To All This Jazz

Hi
I need to create a database where there is one table where data is added however in this table there are a few other tables which are updated from this one table. For instance Supplier and Product when you add in the product and the supplier the supplier field will have a drop down box for the available suppliers and if it is not in the list then you can add it by just typing it in the field. This will update the Supplier table . Or do you have to add all the suppliers into the table and then make a query for the products table that includes the supplier table.

I just need a simple way of not rewriting the same thing over and over
but having all the fields available in one table ??
Hope I make sense