So... First step in making a nether portal:
Place obsidian at the #. ( .. = air)
..##.. /\
#....# |
#....# | height
#....# |
..##.. \/
<------>
width
if you did this right, next step : light a fire up inside that oval.
If noisy violet moving things appear, it's activated.
Last step, step into it and wait as your screen turns violet.
Spawn in the nether...
There you go! You're in the nether and ready to get some glowstone!