I'm sure this is super simple but I can't get it right!

 From:  gunter511
10702.1 
Hi All,

I'd like to make a solid object between the two 'planes' highlighted in yellow, using the rail:



I've tried sweeping and lofting but neither work.

Could someone please tell me the best way to do this?

Many thanks!
Gunter

EDITED: 15 Jul 2024 by GUNTER511