First you need to make a Paddle image, which you've probably already created in the paint program, but if you want you can make a paddle image in DarkBasic
Here's How:
Ink Rgb(255,255,255),0
Create Bitmap 1,100,25
Box 0,0,99,24
Get Image 1,0,0,100,25
Delete Bitmap 1
You can make it look a lot better, but if you want to keep it simple that should do for the paddle image.
However, you can just make a paddle in paint and then load it into DarkBasic.
Here's How:
Load Image "FileName.bmp",1
That's all you got to do, but just make sure you put the real name of your Paddle that you created in the quotes.
So, pick whatever one you want to do either creating the image in Paint or DarkBasic, and put the code at the top of your program.
Then, write this below that for your main loop:
Px=320
Py=400
Do
If RightKey()=1 Then Inc Px
If LeftKey()=1 Then Dec Px
Sprite 1,Px,Py,1
Sync
Loop
Once you've done all that you'll have a simple paddle sprite moving at the bottom of the screen by pressing the right and left keys

.
It might not look like much, but you got to start somewhere. And after you get the paddle moving like I posted above, you can make it move even better and if you want I can show you how, but make sure you understand what I already posted first and if you don't just ask.
Hope I've helped