Who do i contact about being abroad while having a green card?

I have had a Green Card for about 4 years, now and i am planning on going back to my home country for 1 year to work. I know i have to apply for a re-enter permit to be away from the US for more than 6 months, but i don't know who to contact about that. Is it the US consulate or some other type of agency? So getting the number for the right contact would be nice.|||actually, you only need to get a re-entry permit if you're going to be out from 12 to 24 months. however, check out www.uscis.gov and go into the forms section and download the I-131. the instructions are there. you have to apply while you're in the US, and don't leave until you've done the biometric requirement.|||http://www.uscis.gov/portal/site/uscis/m鈥?/a>