There is a row of plastic clips that you must take off under the hood on the top of the bumper and in the large vent on the bumper at the top of the vent.
The clips are easy to see, but there are 2 hidden nuts on each side of the bumper (4 total, I think) that need to be taken off. These nuts connect the front bumper to the front quarter panels. It's best to take out the splash guards in the wheel well or loosen to be able to reach them (as stated above).
Save the clips that you can but you can find replacements if you ruin them. Toyota dealers have them but I've found that a body shop is the best place to find the clips, just take a sample clip to them and they can give you the clips they use. The body shop is going to be cheaper than OEM Toyota clips more than likely.