How to use Transaction in Entity Framework?

How to use transactions in Entity Framework? I read some links on Stackoverflow : Using Transactions or SaveChanges(false) and AcceptAllChanges()?

BUT; i have 3 table so i have 3 entities:

CREATE TABLE Personel 
(PersonelID integer PRIMARY KEY identity not null, 
Ad varchar(30), 
Soyad varchar(30),
Meslek varchar(100),
DogumTarihi datetime,
DogumYeri nvarchar(100),
PirimToplamı float);

Go

create TABLE Prim
(PrimID integer PRIMARY KEY identity not null,
PersonelID integer Foreign KEY references Personel(PersonelID),
SatisTutari int,
Prim float,
SatisTarihi Datetime);

Go

CREATE TABLE Finans 
(ID integer PRIMARY KEY identity not null, 
Tutar float);

Personel, Prim, Finans my tables. If you look Prim table you can see Prim value float value if I write a textbox not float value my transaction must run.

using (TestEntities testCtx = new TestEntities())
{
    using (TransactionScope scope = new TransactionScope())
    {
       // do something...
       testCtx.Personel.SaveChanges();
       // do something...
       testCtx.Prim.SaveChanges();
       // do something...
       testCtx.Finans.SaveChanges();
       scope.Complete();
       success = true;
    }
}

How can I do that?

When you make the call to SaveChanges, the Entity Framework will perform those operations in a single transaction.

When you use the TransactionScope class, you are saying "I want what runs in this block to be encapsulated in a larger transaction", which is indeed what you do.

When you call Complete on the TransactionScope, that is what perform the committing of all of the operations encapsulated in the transaction defined by the TransactionScope.

SaveChanges operates within a transaction. SaveChanges will roll back that transaction and throw an exception if any of the dirty ObjectStateEntry objects cannot be persisted.

from the documentation

There is a similar example in the MSDN site.