In spite of what some people tell you, 3 shots arent usually enough to give you a decent HDR image. Even if your 5100 had AEB for 3 shots, its not enough. So you have to do it manually. Select the best settings for the camera depending on the lighting of the scene. Use the lowest ISO you can, pick an aperture around f11 if possible then pick a shutter speed which will give you the best overall shot. Use that as 0. Then click backwards your shutter speed so you can get 2 shutter speeds underexposed. Take your shot then click forward 1 fstop take your shot. Click forward another fstop bringing you to 0 which is your middle shot. Repeat until you have 2 more shots which will be 2 fstops over the 0. Now you should have 5 shots, 2 under exposed, your middle shot and 2 over exposed (-2EV, -1EV, 0EV, +1EV, +2EV). The aperture has not been moved and remained on f11. The only changes has been the shutter speed. Combine the 5 shots in a program like Photomatix, or HDR Effex Pro and you should get what you want.