how did you get an image in the background as a backdrop anyway after chroma keying???

In order to add a background for green screening...

1. Open a new project
2. Import your background picture
3. Click on Project in the Left collumn and double click on the background file
4. In the larger column on the right, click on current.
5. To change the size of the background click the black button, with a yellow square outline on the inside.
6. Select how much you want to see as your backdrop
7. Click file on the top row, and import your green screen video.
8. Drag the green triangle thingy onto Media Mixer
9. Click Track then Rectangles on the top row
10. Select your Green Screen Video not the back drop.
11. A second box with a picture of your backdrop should open on the side.
12. Click the white button on the right hand side of the box.
13. Your green screened video should appear as a small box inside of your backdrop.
14. Click current in the Right Column and click the black button with the yellow  square inside and select the area you want to see
15. Then go to F/X/ Effect/ Video Effects/ Pixel Filters/ Keying Filters/ Yuv/ Chroma Key
16. Drag the effect onto your original green screen video
17. Press the grey box with the green square inside and select the area you want to key out. For finer adjustments adjust your Y-Tolerance in the Vars Bar
18. Click arrangment on the right column, and in the left column open FX/ Effect/ Video Effects/ Convolution Filters/ Key Smoother
19. Then open the Vars tab and play with it until you're satisfied

Then You Should be done...