Anyone could help me please ? how to do this surface on rhino?

Hi, i start on rhino there is 2 weeks ago, and i would like to know how realise the shape of this hull on the following picture : 36

i start like that, but i have problem to close the underside :

What have io to do with the yellow curve ? or maybe my process is wrong ? what is the right way ?

thanks a lot, and hope get some answers