If you don't know where your Representative stands, now would be a good time to call and ask. The Congressional switchboard is 202-225-3121. Ask to be connected to your Representative's office, and ask your Representative to co-sponsor McGovern's bill [H.R. 2404] and support McGovern's amendment (which is essentially the same text as the bill) when it comes to the floor.
This will mark the first time in the Obama Administration that there has been a debate and vote in the House specifically on U.S. policy towards Afghanistan. The amendment is quite worthy in its own right: do not the Congress and the American people - not to mention the people of Afghanistan - have the right to be told what the exit strategy for the U.S. military is? But it is also a wedge to open up debate in the United States about what the U.S. is doing in Afghanistan and plans to do in the future.
Military commanders have made statements indicating plans to remain in Afghanistan until 2020. If ten more years of war is the Pentagon's "exit strategy," we - and the people of Afghanistan - have a right to know that and debate it.
Since you're calling your Congressional office anyway, let me call three other worthy amendments to your attention.