I need help...

So im trying sumthing new, and id ont understand it

Gfx Toolkit | Create a 3D Glossy Box Logo in Photoshop | Tutorial9

step 1 part 2

Since we want the box to appear as though it is on a surface and not floating in the air, we are going to add another gradient. On a new layer, make a selection about 90px tall from the bottom of your document (depends on the size of your document). Create a radial gradient closer to the left side and towards the top of the selection so that it looks like the one in the image below.

i dont understand a thing hes saying...