A few places where you can easily find where to write or call your members of Congress:
Official starting points:
A couple of useful third-party sites:
www.govtrack.us - enter your address or choose "I'm at home" to use your phone's/computer's location; get info on all three members of Congress. This is a good website for learning about and tracking legislation and votes!
www.votesmart.org (autoplaying video on home page) - enter your zip code, then scroll down past the president, VP, cabinet secretaries, etc.; your senators and representative will be above state and local officials. Then choose "Bio". This site has the advantage of showing the member's state/district office addresses and phone numbers, in addition to their website and Washington DC office info.
(Vote Smart also compiles ratings and endorsements from hundreds of advocacy groups.)
Reportedly you'll get a better response from your representative's or senators' local offices than from their DC offices. (No reason you can't "vote" twice, though!)
Here's today's letter to a PA Senator. If you're not from PA, just leave out the first two paragraphs.
Dear Senator Toomey,
I feel as if you’ve betrayed the interests of ordinary people, by voting to confirm James Mattis, John Kelly, Mike Pompeo, Nikki Haley, Elaine Chao, Rex Tillerson, and Elisabeth DeVos.
I urge you to oppose Jeff Sessions for Attorney General, based on his racist history. Silencing Elizabeth Warren was wrong.
Oppose Scott Pruitt for EPA Administrator, since he’s opposed to everything they’re mandated to perform.
Oppose Tom Price for Secretary of Health and Services. His loud criticism of the Affordable Care Act shows he’s not in favor of ordinary people getting health care.
Democracy is under attack by ChristoFascists like Pence and Bannon, who seek a theocracy instead. Nobody else wants a Christian Holy War against Islamic countries. As a Republican Senator you must resist the ChristoFascist’s stealthy insurgency, or democracy-loving citizens will vote you out. In 2016 you won by less than 2%.
You swore to uphold the constitution. As a religious person, you must know that the Founding Fathers are watching you.
Your concerned constituent,
Why not use their theism.