How to close my model in a proper way As on the image, I want to close his back and front but I don't want to look like a cube or plane.
I want how to it's details like belly,nose,mouth,eye and so on.
However I try, I can't add the vertices/lines so I can create details.
I just want to make a low poly orc, if you can help me out I would appreciate it a lot.
Thanks in advance and hope you respond. :)

(Sorry if I posted wrongly or something else since this is my first question)
You can use the Grid Fill option to create many faces.

Select the edge loop (Alt + RMB), key Space, type Grid Fill, and select the option.



Example on a cylinder: