Registration of FLAIR MRI with segmented glioma with anatomical atlas

Hello, I am fairly new to 3d slicer.

My aim is to determine the position and infiltration of a glioma with the insular cortex. I have segmented the tumour. I am unsure where to go from here. Would I need to register with an anatomical atlas or somehow crop the glioma and fuse with the atlas?

I would be very grateful for some advice.