>I'm writting an application, but i can't pass this point. One of my forms uses a document id that must be the some in other table. After the user confirm all the data the program must write the new record in the first table and write the new value in the other table. This seems very simple but in fact i can't make it over. Can someone give-me a hint ?? TIA.

It looks like job for INSERT trigger. Set insert trigger stored procedure which will change values in second table. Also if you have explicit relationship between tables you can use UPDATE-SQL command.