It goes something like:

from t1 in db.Table1
join t2 in db.Table2 on t1.field equals t2.field
select new { t1.field2, t2.field3}

It would be nice to have sensible names and fields for your tables for a better example. 🙂

Update

I think for your query this might be more appropriate:

var dealercontacts = from contact in DealerContact
                     join dealer in Dealer on contact.DealerId equals dealer.ID
                     select contact;

Since you are looking for the contacts, not the dealers.