Adding more RAM to your Minecraft is not an uphill task, but the first thing you have to do is to check the ram that is available on your PC itself.
1. Go through these steps: Start - Settings - About. Under the device specifications, check for the installed ram. If you have 2 or more GB of rams, you are good to go.
2. Launch your Minecraft launcher and choose the version you would like to play.
3. Check the tabs at the top, and you will see a tab named "installations" select it, and you will see some drop-down options.
4. Place your cursor on it, and you will see three white dots towards the right side, click on it, and click edit.
5. A window will appear with the installation name, version, and some other settings. Select "more options" and check the options below; you will see JVM arguments.
6. In the JVM arguments box, there will be quite a lot of codes in it, but the part with -Xmx2G is what we are dealing with.
7. Change figure 2 there to the amount of RAM you want your Minecraft to use.