smee: command not found

In this gitHub guide for creating a gitHub App , when i run

npm install --global smee-client // this command runs correctly, returning

/home/<myusername>/.npm-global/bin/smee -> /home/<myusername>/.npm-global/lib/node_modules/smee-client/bin/smee.js
+ smee-client@1.0.2
updated 1 package in 12.784s

 but when i run, 

smee -u https://smee.io/uu7HyIoJ2hlyNp3 // this returns

No command 'smee' found, did you mean:
Command 'smem' from package 'smem' (universe)
Command 'see' from package 'mime-support' (main)
Command 'smew' from package 'mew-bin' (universe)
Command 'smew' from package 'mew-beta-bin' (universe)
smee: command not found

so am wondering what could be the error, could anyone help?

Most likely your global Node modules directory is not in your PATH. Check the npm documentation for more information.