Curve Inside Corners Of Shape

[Goosekeeper]

I’m brand new to vector stuff so I’m not sure how to word things. 

Trying to build a vector version of a logo I made in photoshop. Was able to round the outside corners but cannot figure out how to round the inside corners. 

Thanks :)

[DM1]

Copy the first shape and resize ir to fit inside the first shape. Select both layers and in menu select subtract.

[Alfred]

Alternatively, use the Corner Tool: