<p>I will explain problem with an example:</p>

<p>There is two table in my database, named entry, tags</p>

<p>There is a column named ID_ENTRY in both table. When I add a record to table, entry, I have to take the ID_ENTRY of last added record and add it to table, tags. How can I do it?</p>

I would probably do this with an INSERT trigger on the named entry table, if you have all of the data you need to push to the tags table available.  If not, then you might want to consider using a stored procedure that creates both inside a transaction.
If you want to do it in code, you'll need to be more specific about how you are managing your data.  Are you using DataAdapter, DataTables, LINQ, NHibernate, ...?  Essentially, you need to wrap both inserts inside a transaction of some sort so that either inserts get executed or neither do, but the means to doing that depend on what technology you are using to interact with the database.