Summarize:

Saw the 2 8ft (2.4m) 2x6 (38mm x 140mm) boards in half lengthwise to get 4 48 inches (120cm) wooden pieces. Do the same for the 2 6ft (1.8m) 2x6s (38mm x 140mm) to create 4 36in (91cm) pieces. Together, these components will form the basic structure of your horseshoe pit. If you think you might want backboards for your horseshoe pits, go ahead and cut 3 3ft (0.91m) 2x6 (38mm x 140mm) boards and 2 2ft (0.61m) 2x2s (38mm x 38mm), as well. Use a circular saw to cut your boards quickly and efficiently. If you don't have a circular saw, you can also saw the boards by hand, or have your supplier cut your lumber to your preferred dimensions before bringing it home. Always wear thick, rugged work gloves and protective eyewear anytime you're operating a power saw to keep yourself safe.
Cut your lumber to the appropriate size.