Welcome to the forum. There are a number of us here including me that were long time photographers who dropped photography for a number of years and came back.
This is a great place to pick back up on the hobby.
Be sure to add your camera gear to your profile so when you ask questions we can help you better.
Under camera just put the model number like D7100; Once you put the first letter like D you will see a list of all the cameras in the database pop up. The more numbers you put in the smaller the list becomes. When you see your camera just click on it, Be sure to click on "Save Changes" in the lower right corner.