how do i get a different area of a sketch to extrude?

gonzo_torpedo

So i'm super new to Onshape, and have made my way through a few tutorials, but have hit a snag while trying to do something that i believe should be fairly simple -- yet i can't find any helpful info on how to do it. I suspect i'm doing something wrong.

I'm making an extremely simple part. Check the link to give it a look.
https://cad.onshape.com/documents/25c27b313c8578c97d7b16a0/w/6bae8062a511eecc73933ebf/e/cae39b3574a5d74b441d7832

the issue is that after making my sketch, when I hit the Extrude button, the software chooses the wrong part of the sketch to extrude. It does the big area in the center, which i need to keep empty. what i want to extrude is the closed area just outside of that -- the part that forms a vaguely clothes-hanger-ish shape with that boxy hook at the top left. I tried to override that by manually selecting all the edges and extruding those, but now i just have a skeleton, and the area i need to fill is still hollow. 

Anybody know what i'm doing wrong? 

grochino

Welcome to Onshape! This will happen if you do not have a closed sketch. To troubleshoot where the gap is, I draw lines in the profile to narrow down where the opening might be. Once you close the gaps, then your Extrude will succeed.

See my animation below:

gonzo_torpedo

thank you @gaby_rochino!