Programming
I have been programming since the year 2004, and the enthusiasm hasn't lowered at all: in 2014 I coded some programs for the Nokia 9210. I have written an OPL beginner's guide, and its link can be found at the end of this page.
OPL
General
OPL, which stands for "Open Programming Language" (earlier Organiser Programming Language), is a programming language developed for EPOC and Symbian operating systems. It resembles the BASIC programming language heavily, and it's a high-level language with a more gentle learning curve than e.g. in C++.
The first OPL version can be found from the 1986's Psion Organiser II handheld computers. After Psion retired from the handheld market, OPL became open source and its name was changed into current Open Programming Language. At present OPL's support has got stuck into Symbian OS v7.0s and earlier, as the OPL development team's motivation and size aren't very big at the moment; Nokia and Sony Ericsson haven't showed any willingness to be developers of this programming language.
A quick look into programming
OPL is a beginner-friendly programming language, because with it the programmer can achieve dashing results with only a few lines of code: for example, loading an image to Nokia 9210's screen looks like this:
PROC ShowImage:
LOCAL Image%
Image%=gLOADBIT("C:\Image.mbm")
gUSE 1
gAT 0,0
gCOPY Image%,0,0,640,200,0
gCLOSE Image%
ENDP
That's it. Fairly simple, isn't it? More of this can be found at the programming guide at the bottom of this page.
OPL is so-called procedural programming language, which means that it proceeds with code chunks named procedures (as you can see from my example: PROC starts the procedure and ENDP ends it). There can be as many procedures in the source code as the programmer wants, and they don't have any length restrictions. Still the source file should be splitted into multiple PROC chunks in the name of readability.
One can have no programming history to start learning OPL; it's enough that the subject interests. In addition to that, you'll need a device that supports OPL, but if you don't have such, you can also develop applications onto the device emulator (the programs written onto the emulator work on the phone as well).
OPL programming guide
Covers a few basic things in OPL, and all the things have been explained very thoroughly.