Where did you install git to? Different install methods will put it in different places. Double check your install process. On my machine i have it in /usr/bin/
You need to ensure your PATH contains the directory that the git lives in.
You can either run locate git to search for it, you'll probably have to build your locate database if you haven't already.
Of you can just try a few typical places
/usr/bin/git --version
Once you know where it is installed, can modify your PATH file by editing .profile or .bash_profile to add the appropriate value.
Best Answer
Turns out I didn't have powerline font.
You can get it from here
After download, double click to install and set as defalut font & non-ascii font