Te get British Airways Executive Club Silver card You had to fly 2 times with BA and earn total 600 Tier Points. If You will sign in to Executive Club just day before You will have Silver status for 2 Years, after then You will drop to Bronze.
BA just put grate fare from Amsterdam to US in Business Class. You can go to many cities like New York, Los Angeles even Alaska (ANC and FAI). You can earn us much 920 Tier points for route AMS-LHR-JFK-PHX-ANC-PHX-PHL-LHR-AMS as well up to 42000 avios if You olready Gold card holder with BA.
You can book it with BA only by calling them You should check first availability using http://matrix.itasoftware.com