Need some basic help playing LoL

Having locked camera to a free camera or prefixed locked requires some time to adjust to, you have to work at 1 thing at a time, get comfortable with the game first, literally just play the game, focus on getting accustomed to "feeling" the game, then you can make certain changes that appeals to you or the champions you play and/or role.

After you've gained certain familiarity with the game that's when you start making custom changes, for last hitting, literally just go to practice tool, spawn the minions and try to last hit them, recall base buy items, and keep going that way, buy different starting items, learn how to last hit at what certain % would grant you the last hit, later on you'll learn wave management, what you should focus on when you push, how to break a freeze, reset your lane and or freeze your lane etc, those are all advanced lane mechanics that you will learn later on as you're more of an advanced player.

Back to the camera, keep it locked, focus on the last hitting and your mouse settings, there should be an option that under game that treats "Target Champion only" as toggle, you should check that, and bind that key to something comfortable for you, so you toggle that when you want to attack champions in between waves or minions or behind towers.

After you played with locked camera a while you will then be able to play with free camera, but use space to center the camera back onto your champion (holding space down keeps the camera locked, which can be a good tool if you want to have the camera locked for a certain fight or whatever you're trying to do.)

Map awareness comes with familiarity, pay attention to pings, when you hear pings on the game, pay attention to your map, everytime you hear a ping, look at the map, what's being pinged, you dont need to look towards whatever is being pinged for now, just get accustomed with the reaction of the pings and paying attention to the mini map. Make it a habit to pay attention to the map when you're safely behind minions, a glimpse will do, every 5-10 seconds, later on more frequent. Make sure you pay attention to who is missing on the map, as your teammates wont always ping you, and as an ADC that can put you in a bad position