I see you are a new user here - welcome to the forums!
As someone who made the leap from BlackBerry to Android a handful of years ago, I understand that this "adjustment" period may be a little confusing and/or overwhelming for you. Do not worry - you'll get used to everything in no time! Here are some personal suggestions, if you like:
- try not to do everything all in one day. Adjust your wallpaper, look at widgets to use, and then maybe leave it at that. Doing too much at one time could frustrate you
- download Zedge - it's a free wallpaper/ringtone/notification/icon pack app; and it's amazing
- maybe stick with the launcher that came with your phone right now; at least until you get used to Samsung's operating system. A new launcher will totally change the look of your phone; which is cool but it may make things more confusing
- Google, ask, and YouTube! As in, Google for questions, ask other users for assistance, and YouTube search tips and tricks for your phone! YouTube has come in handy for me when I need to troubleshoot or set something up on my phone(s)
Please feel free to ask us for any further help, and enjoy your Samsung phone!
Oh, whoops, I forgot to tell you what I was doing with my own phone LOOL. I have an Honor 8, running the launcher that came with the phone; however, I am using a Pixel 2 theme as my setup. Themes are great, because they change the appearance of your phone (ie, icon pack, on-screen keys, etc); but not the overall look and operation of your phone, like launchers do. It's a good "middle step" if you're looking to change up your experience a little bit.