Fencing the Yard

In general, very few improvements raise the selling price of a house by the amount invested -- no matter what they say in remodeling magazines. Most should be done for your own satisfaction and use.
 But in any case, the answer to your question depends on a lot of things I can't judge from here -- price levels in your neighborhood, size of your lot, whether other yards are fenced, how much you intend to spend and what type of fence you are considering. 
Call a few local real estate brokers and ask for their opinions, perhaps just over the phone.  They can judge better than I can.