Creating a face

Hello all,
Im kinda new to using sketch up and self teaching while im on a project for uni. I am currently creating a bench that has curves in it. currently im trying to make a face but sketch up won’t auto gen one which is starting to get frustrating. I can’t work out why so im here to ask you all for help.

Screenshot 2021-01-09 at 14.05.58|689x474

One way

Hiya thank you so much.
That worked perfectly. I shall have to remember that.

hello sorry another question am I able to offset into the curved shape?

also without plugins