how to align a form and an object

[miaoke6P3L2]

Hi

I think this must be very simple to do, but I don't know how to do it.

I just wanted to align the yellow object with the grey object, to make the yellow one sits on top of the grey one. Basically I wanted to make it looks like the file I attached, but I aligned by eye.

Thank you

[TheCADWhisperer]

@miaoke6P3L2 

There is a lot of symmetry in your design.

I would make use of that symmetry modeling about the origin.

I would fully define each and every sketch (no blue curves or white dots).

I would not have ANY unresolved issues highlighted in red or yellow in the Timeline. 

Stop immediately and ask questions when you see unresolved issues highlighted in the Timeline.

I would use Components and Joints or Assembly Constraints.

I would not use Move.

Are you ready to start over from scratch?