I'm thinking about bricking over my exsisting concrete patio. The concrete is not sealed and it is slightly textured. Do I need to prep the concrete at all? How do I make an edging? Any help would be greatly appreciated!

Are you planning to set the bricks in mortar or just sand?

I would recommend using a 2" - 3" sand base over the existing concrete (in addition to providing protection from movement by the underlying concrete it should allow more flexibility for setting a new degree of slope that you may need for a brick surface). As far as the edge goes... if you use sand you'll have a little space at the edges to use bricks for your border.

If your patio is above grade you could build a border with pressure treated lumber glued and screwed to the concrete. That would hold back the sand and keep the edge brick from moving or flipping.

Here's My Opinion, The Fact That It Isn't Sealed To Me Is Good, You Do Need To Clean It, Get The Dirt Off, As Far As Texture Its Most Likely A Broom Finish, Which Is Fine To Lay On. Id Use Brick Motar To Lay All The Brick, You Will Need To Slop It One Way And Make Sure As Your Laying The Brick That There Are No Dip Where When It Rains You'll Have Puddles, As Far As Motar Goes Id Say At least An 1" Bed Would Be Enough. Maybe Alittle More For Slope To Be Taken Into Play,

Before You Start Set A Level On The Pad You Have I Bet It Is Already Sloped
If So Just Run With That.
As Far As A Border, Just Use Some Pavers Like Everywhere Else And Run A Boarder With That, Depending On You Pattern Youll Have To Cut The Brick Up To It. No Bigger There.

As Far As The Other Comment About 2 T 3" Sand Bed, Ive Only Done That When Were Layen On Dirt, Well Lay 2 To 3 Of Crush And Run Gravel. Then Screed It All Out To Be Level Or Slope Whichever But Making Sure There's No Dips, Then Lay The Brick , After This Take More Crush And Run Gravel And Spead It Over All The Brick, Take A Shop Push Broom And Work All The Gravel Between The Brick, After This Lay A Hose To It, Don't Dround The Brick Just Lightly Spay It, And Put More Crush And Run Down And Do It Again, This Will Keep All The Brick Put.
Hope That Helps