I gave you two options.
1. Buy and start with the examples with an LPCXpresso development board. (This would set you on the path for NXP LPC)
2. Buy and start with the examples with an ST32 Discovery development board. (This would set you on the path for ST ST32)
The NXP and ST Cortex-M lines are the most accessible with a cheap development board and programmer and a good selection of readily available chips.
I've played around with ST and TI Stellaris (now Tiva), but the main manufacturer I use is NXP for the LPC13xx and LPC17xx line.
You've gone with neither of the options I gave, so I can't help you. If you do not know C and do not already have a good handle with microcontroller development then you should pass this up for now. Cortex-M3 is simpler than the old ARM7, but it's still a step up in complexity from regular 8 and 16 bit chips. Based on that thread and your question that you don't know what to look for, I suggest waiting to do this later.