depending on what You like to get, but normally You create one feture out of on sketch rectangle and then make a pattern of that 3D feature.
I think that this is the reason for a not perfect 2D pattern functionality.
Although it exits if I remember correctly.
The rectangular and circular patterns shown in the top left only appear when I'm in 2D sketch mode. There must be a way to pattern a 2D geometry.
When I have a 3D feature, the pattern and mirror options are on a different tab labeled Pattern. This one I know how to use.
It's not for patterning 2D stuff. You can use a sketch pattern in a part to pattern features or assembly to pattern parts and assemblies.
The neat thing about having a sketch define a pattern is that you can use it multiple times in say, an assembly where you want to define discrete but identical patterns of different parts of your assembly at different times.
There's no patterning of 2D objects in part or assembly sketches. I wonder why you would want to. As Tushar said you can pattern 2D objects in a draft.
It seems I was late for "this party".
Solid Edge handles this on "feature level" not sketch level... Sometimes it is useful and sometimes not...
Here is a video about this: