I use a 2014 laptop with Intel Core i5(2010) with Windows 7 Pro Extended Support(2020) I want to do modeling with Unity but I tried but it said you need a high level computer while i have a mid level
All you need is to go to the Blender.org website and there should be a big "Download" with the name of the most recent version. Just click that and it will take you to a download page where you select your operating system. If it doesn't ask it might detect what you have already. You most likely have 32 bit so if it asks for "16 bit or 32 bit" choose the 32 option. If that doesn't run you could try downloading the other version later. After you hit the big download button, it should proceed to download. If you are using Chrome or most causal web browsers you should be able to see it in progress on the bottom of your screen. When it is done you can select it.
The installer will show up and then you can just keep hitting "next" until you finish the installer. You should make sure the "Add shortcut to desktop" is checked. Then you can start it by starting the shortcut that is now on your desktop.
Your computer should be able to run Blender just fine. However, you might start seeing some lag if you start making anything too complex. If you are just starting out make simple things and if you want to make a lot of objects use different files instead of having everything in the same file. This will make sure Blender is only using the memory that you want it to.