Hey buddy,
If you're not a scripter, then I can safely say that a complete "Chat" system is not an easy thing to create (I actually created one that's available on the Skyline Store and it took me quite a while to get it to work correctly!).
To learn Lua, the best place to start would be to buy one of the many Lua books out there, or you could use one of these online resources:
"Programming in Lua" -
"Lua Programming" -
Finally, there's also a tutorial here:
The main thing to be careful of is the actual version of Lua (I think Skyline is still on v5.1) as things have changed between versions, but these changes probably won't affect someone just starting out
Regards
Shando
PS: If you get really stuck, try googling as places like Stackoverflow () have heaps of knowledge available with a simple Google search

Failing that, just ask here and we'll certainly try our best to help!
PPS: You could also take a look at this forum post which uses a pop-up when a player enters a trigger volume