I'm working with a .CATpart file, while editing in part design I'm not able to create pockets in this model. I switch to Wireframe and Surface but I'm not aware of which function will help me achieve the same result as pocketing, please help!

The pocket command may be grayed out because there is no solid geometry to remove a pocket from. In other words; the file is a surface model and not solid.

If that is the case, you can use the Wireframe and Surface workbench to draw all the edges of the pocket and then add all the faces/surfaces. You will also have to define the hole in the wing surface where the pocket is.

Here are the few steps that to be followed
1. Some sketch based features like pocket, groove etc., will be visible when you create any solid model denoted in some-what Grey color.

2.Also it seems that you are working with surface denoted with yellow color. So in that case you will be able to use pocket since it is solid based Feature. To create a hole there are two ways:

2.1. First using split command in surface workbench, in split, choose element and cutting sketch. For more clarity refer youtube videos.

2.2. Use of thick surface in part workbench converts to solid then you can able to pocket the solid. There are many things concerned with thick surface, you have make all surface as single piece using join command in surface workbench before using thick surface in part workbench.