Have you tried the Makehuman programme to make your character and Rigify to rig it? Someone has already done all the hard work for you…
I have just looked at your blend file - ALL your IK constraints are invalid, that’s what the red box means as shown in my picture below:
You have NO targets so the IK’s won’t work. You must add target bones and use the tail of these as you IK target. Take a look at the manual pages for IK constraints, or get yourself MakeHuman and activate the Rigify add-on, this will get you going in the right direction. Also you should have a “root” bone on the floor to which you IK targets are to be parented, this allows you to manipulate the entire character or various parts individually.
Next issue is that your mesh is all tris (three sided faces) - not a quad (four sided face) in sight - not good.
Finally you bone naming convention is not good. Bones should be of the order “arm_upper.L” “arm-upper.R” ,etc. (note the .L and .R bits…) this will greatly assist you in posing your character as it allow you to “Paste Opposite” to reverse the pose for walking for example. Can I suggest you read the Gus tutorial here:
This will get you going in the right direction. Also you have bad edge loops and no Sub-division Modifier to make your vertex count low and your render smooth.
If you look at your mesh in Weight Paint mode and select the bones in the vertex groups panel, you will see that you weights are all over the place.
Sorry to be critical, but you need to hear all this to get back on track.
Just noticed one other thing - here’s the test:
Rotate one of the bones, like the left shin bone, round and round and then press escape - the bone should return to its rest position - your doesn’t this means constraint errors or cyclic dependency errors, both need fixing I am afraid.