Now let us add 3 more segments to the box where the joints are supposed to be. When tweaking with it, make sure that you match it with the reference image as shown below. We can add edge loops in couple of ways, by either right clicking on the viewport and clicking on the box next to “Connect” option or you can see the option in the command panel when you’re in vertex or edge mode etc. Don’t add more segments as we’re working on a low poly character, off course you can add segments but only in the place where you need them because in the end you’ll find it to be high mesh model and will be problematic while rendering, saving etc., as it consumes more of RAM unnecessarily.

Take a look at the below image to see how I have placed the vertex and the segments and matched it according to the reference image. Now select the corner vertex of the finger and push them down.

You can also see how I have pushed the edge loop of joint to the upper in the below image.