You have to direct your friend to Website & the Game and Lobby you're currently in.
Example:
Hey there, I'm in 8Ball Pool in Room 1, waiting for you.
(you would share with him/her this link) Go to this Link :
http://www.flyordie.com/8ballpool/
and Click Play Now to be prompted to enter your login information and then proceed to load & I will send you a game request once i see you in the lobby. (if clicked via Play Now it will load a lobby list showing room names/numbers, which will then give the user options to choose where to login, however below the PLAY NOW button there should be a list of rooms anyway so it's easy to navigate and meet up.
Obviously it doesn't have to be 8ball, can be whichever game you're playing lol.
If he/she is a regular then you should both realistically know by now exactly how you can meet and play each other on the games. Unfortunately there's to way to Locate and invite outside of a Game lobby Dear, sorry.
Kind Regards,
