How do I change the size of part of a background?

So I'm very new to Construct 2 (started today) as well as making games in general. I'm trying to make a background and have started with a couch. on the couch I put a red pillow. However, I realized the pillow is too small. Is there someway for me to use the select tool to select a square surrounding the pillow and make it bigger? This would be similar to free transform in photoshop (control t). I can only figure out how to resize the background in it's entirety, not just the selected part.

Thanks for any help. Sorry if I am not clear

Also I am wondering how to draw a curved line, which I am not sure how to do. I can do it manually with the pencil tool, but not sure if there is a tool to do so

You can select the object with your mouse, and a blue square will appear around it, hover on the edges of the square and you will see a white point, click there and drag it to resize, also on the left side of your screen you can see input fields for the selected object, there's a filed called size you can use it to change the select object size in pixel's ( example 20,20).

As for the curved lines, construct uses images for the graphics rendering, so if you want a curve line you will have to draw it first on paint or photo stop then you will have to import the image into construct.

If you are new to construct I suggest you start by reading the manual first

https://www.scirra.com/manual/1/construct-2