We actually did not.
They were part of the Mujahideen who were resisting the Russian invasion back in the 80's
No they were not (although I'm not surprised you believe this, since this particular lie has been repeated so often). The Taliban was a school of Islamic religious thought (in Pakistan) at the time and weren't a significant force involved in fighting against the Soviets. They merely exploited the power vacuum that existed after the Soviets left to establish their "ideal" Islamic republic. They did not appear as a political or military force in Afghanistan until after the CIA stopped providing aid in 1992. After that time, the mujaheddin resistance continued to fight against the Khalq (Soviet backed, although the Soviets themselves had already left) regime for control of Kabul. Just as the Mujaheddin victory seemed secure (after both the Soviets and the CIA were no longer funding either side), the Taliban emerged as a political and military force and drove the mujaheddin into a small enclave in the north-eastern part of Afghanistan, where it became the Northern Alliance (the same group to whom we later gave assistance to help overthrow the Taliban; the Taliban were never able to completely eliminate them nor take control of Afghanistan completely).
Please note, however, that we DID give support to the Taliban during the Clinton administration (long after the Soviets had retreated); this was primarily bribes under the "war on drugs" to convince them to combat the farming of poppies and the opium trade.