I can't light up the nether portal I tried 1000 times and did not work

make sure you are trying to light the obsidian blacks on the bottom of the frame ad that the frame is the correct size. This should really go to the forums.

@Bob Dobbs
You can actually light any block since the 1.7 snapshots

@Topic
How big is your portal? Is your client vanilla? Can you please attach screenshots?