Ionic Framework Errors

I have started making Ionic apps a while a go, and have stopped and recently I decided to start a new project, opened the Git Bash and typed ionic start AppName tabs and I got this error sh.exe": ionic: command not found. I searched in the online framework docs and forums and found out that the ionic needs to be updated. I didn’t know how to do so and kept searching and I found another command which is npm install -g ionic. I then got another error : Error: EPERM, mkdir 'C:\Program Files (x86)\Git\local' at Error (native)

I am typing the commands in my Desktop

I am running Windows 10.