What is meant by do what you can with what you have where you are?

It means to make the best of what you have, what you can do with it and the best of where you are at the time.

Say you're camping and there's no electricity so you can't plug in your electric coffee pot. You have coffee, drinking water, a pot. You're in the woods so you have wood that you can start a campfire with. Perhaps you've got some eggs, too. You can make camping coffee. You put your water, your coffee grounds in and some egg shells (not the egg). Well you boil it all together and the egg shells cause the grounds to settle at the bottom of the pot and Voila, you've got coffee! That's an example of doing what you can with what you have where you are.