Please have your internet cable connected to your raspberry pi, because in this method we gonna download and install retro pie in the terminal window. Also it will update files when installing Raspbian.
First thing to do is to format your micro sd card with sdformatter
https://www.sdcard.org/downloads/formatter_4/. If you are on a mac just go to application > utilitis> disk utilitis> choose fat and erase
I will keep it as clear as possible, first get noobz from https://www.raspberrypi.org/downloads/
Unzip het and open the main map. These files copy and paste in the micro sd card. Then put your sd card in the raspberry pi and power it on. It will go to os installation, then you will see software which you wanna install. Just choose Raspbian, then it will take about 20 min to install. When its finished and rebooted to OS Raspbian. Select A terminal window in the top left corner, click on it. A window pop up where you can typ your commands.
In this terminal window we gonna enable the 512 mb. (It only works in the terminal window while your still in Raspbian os, keep that in mind.)
Follow the steps in the tutorial link below.
In the last step type free -m
to see if you really have enabled the 512mb or not. In the raspi config the max memory you can set is 256mb and not higher. If you do input higher number then the raspberry pi will be out of memory and you need to start from the beginning again.
Dont worry when you have enabled the 512 mb the raspberry is using its memory for browsing or gaming.
After you rebooted, click again the terminal window in Raspbian os.
Now we gonna download and install retropie from the internet within the terminal window.
Follow these steps in the link below
Typ exactly as shown. example :
sudo apt-get update (enter to load this command)
sudo apt-get install -y git dialog (enter to load this command)
Some command line does nothing like cd, chmod +x retropie_setup.sh just typ the next command code and move on. When its all finished downloading and installing. You will be seeing a grey screen. Choose the first one and install Binaries Based Installation (The basic install). This will install retropie, it takes about 45 minutes and the screen will go black, but thats just the screen saver or something, you know when its finished if the green light on the raspberry stops thinking and flashing for 3 minutes, When you know for sure its finished then press the arrow key on the keyboard to get out of black screen energy saver. Of course when you boot it will boot first Raspbian, but its handy when starting up to choose and type startx (go to OS) or emulationstation(retropie). To do this go to sudo raspi-config and go to boot and choose the second option
"Text Console, automatically logged in a 'pi' user"
In case you need to login your default username and password see below the login default.
It wasnt easy, it takes along time to install. I hope this helps for people who are in the same problem as me. Subscribe to my youtube to support me Thanks :). https://www.youtube.com/user/soulesx3