For the terrain, I just cut up a box of cardboard and glued pieces together until it looked decent. Then spray painted them with grey. If I am feeling real crazy I may do some dry brushing to make them look better! 

For the units, I would suggest printing out little imagines of the units you want and playing with those. Honestly, anything you can find that is the right size will work though if you don't have a printer. 

If you're looking for inspiration go check or r/poorhammer lots of good stuff over there !