From my understanding:
The Supreme Court of Thailand had ruled against the Adjustment Constitution and the amnesty law created by the Peurthai administrative (govt). Peurthai administrative were not happy, went against, and overruled the Supreme Court. An estimated of two million citizens of Thailand protested against the Peurthai or any supporters of Thaksin (former PM of Thailand; brother of current PM Yingluck) to keep the Constitution and to kick all Peurthai out as they are no longer the government in the eyes, mind, and heart of the Citizens.
PM Yingluck announced curfews to stop all protesters and assembly across the metro Bangkok and surrounding provinces but it was no use. Even the Police Department is unable to regulate or stop the protester and the roles have reverse against them. Majority of the citizens feels that since the government does not even honor their own Constitution, therefore cannot be in office.
The citizens also believe the media supports Thaksin due to all benefits from personal business wealth. They also protest against all media who supports the government of Thaksin. Right now the citizens has raided, control, and shut down the Ministry of Finance which is the root of supporting the government including: the Budget Bureau, the Office of Auditor General of Thailand, the Treasury Department, Government Saving Bank, Public Relations Department, and the Ministry of Foreign Affair. Without the Budget Bureau, there's no money invested to support any service and no one is able to work.