Restaurant Picks in Sunset Park area of Brooklyn
It depends a lot on what kind of food you are looking for. 49th St and 5th ave is in the midst of a major mexican/central american commercial strip and what you will find there are rather casual tacos places, primarily. with some ecuadorean and dominican places mixed in. Tacos Matamoros is a very giid and cheery place and its near you, but there are others
If you would prefer Chinese, the Brooklyn Chinatown is on 8th Ave. between roughtly 60th St. and 43rd street (thinning out at that in. as another poster has suggested, Metro Cafe is a good one there (51st and 8th) very casual very authentic szechuan food, formica and chinese tv going. Apart from walking the three long blocks Im not sure how you get over there, check hopstop for transit/walking suggestions.
If you want more upscale, you can take the 5th Ave bus or 4th Ave subway down to Park Slope, huge range of food, I recc. great Italian at Al di La but no reservations in main rest. get there early (6pm) or go to winebar on side, same food., Carroll St and 5th Ave.
Lastly, if you are interested in Middle Eastern food, Bay Ridge is also a short hop away, on the 5th Ave bus or 4th Ave R (local train). There are some grill type restaurants on 5th around 70th, (also a Brazilian grill closer to 67th, if its still open) and there is also Tanoreen on 3rd Ave.(R train for that) Others can give more info or you can do a search if these are to your taste.
Try searching the board for Sunset Park - there are a number of threads that would be relevant. Most of the eating experiences around here are very casual and inexpensive -- to get you started: very casual Ricos Tacos (51st? above 5th) or more restauranty Tacos Matamoros (on 5th btwn 45th and 46th). On 8th Ave, I can't get enough of the hole in the wall Yun Nan Flavor Snack Shop (49th below 8th) and I'm liking Metrocafe a lot (51stish and 8th) these days. There are a lot more specific recommendations in other threads.