The chance of encountering or hatching a shiny Pokemon is usually a 1 in 8,192 chance. The odds are against you, but it's not impossible.
Another way you can get shiny Pokemon is to get an event-download Pokemon that's shiny (one such event just ended; there are no event Pokemon available for Black/White/Black2/White2 at the moment).
If you have Black2/White2 or HeartGold/SoulSilver, some in-game event Pokemon that you can encounter are always shiny. Also, Black2/White2 has the Shiny Charm as a reward for completing the national Pokedex, which raises the chance of finding shiny Pokemon to something like 1 in 2730, IIRC.
You can also use the Masuda Method (search the forums for more information) to try to improve your odds, but you'll need a "foreign Pokemon" to do it.
As a last resort, you can always try asking for a shiny Pokemon on the trade boards, here.
I just got the Shiny Charm myself two days ago. Its worthless in my opinion.
Post game, I'm still roaming around in the game doing things here and there. I even went back to the Floccey ranch farm town and went and caught another low level Psyduck. Right now Im leveling that Psyduck up at the Floccey ranch along with the Shiny Gible that I got from Benga
So Im pretty much walking around in the grass trying to encounter at least a Shiny Mareep or something but no luck at all. Not even a freakin shiny lilipup.
WizardofHoth: See my reply to you in your other topic (http://www.gamefaqs.com/boards/661226-pokemon-black-version-2/67620801). Discussing the Shiny Charm is a little off-topic, here, since this is the White Version board, and the Shiny Charm is only available in Black 2/White 2.