Your satellite receiver should have it's own card and needs to be activated and added to your existing account. We take one of our HD receivers from home and use it in our RV. We purchased a Directv HD satellite dish from Ebay and mounted it on a stand, takes us just a few minutes to set-up as we have the routine down to a science.
There are automatic satellite dishes available that can locate and acquire Directv programming, be aware that many of these automated dish systems (domes) can not provide Directv HD content as it requires a specific roof-mounted system that is capable of locking into multiple satellites at the same time. Camping World has a good selection to choose from and currently has installation specials if going with the costly roof-mounted, automated HD satellite system.
Although we don't always have time to watch a lot of television while RVing, it's great to be able to watch all the same channels we have at home and not miss any important televised sporting events that occur while on the road.