Samsung Galaxy J7 is powered by a Qualcomm Snapdragon 615 processor and 1.5GB of RAM. It features a Super AMOLED 5.5″ display, 16GB internal storage, with up to a further 128GB available via microSD, and wireless charging capability. The rear facing shooter comes in at 13MP and features an f1.9 aperture, auto laser focus while the front camera is 5MP.
Samsung Galaxy J7 is a mid-range device so it will take some time for Samsung to roll out official Marshmallow update. Till then, you can make use of CM 13 custom ROM. This ROM will update Galaxy J7 to Android 6.0.1. A detailed guide is given below.