Need more info. Are you making a walkway, a floor, steps? If a walkway you dig out the area where you want walkway at least 4" deep and try to keep bottom level. Usually made in sections with expansion joint(check with hardware) between. If a large job call company to deliver it. They can help you on how much to get. I have forgotten the formula to figure how many yards. Something about length X width and a certain depth is what I forgot. If it's just a simple above ground platform Lay out 2X4's where you want it. Remove just the top couple of inches of soil/grass. Place 2X4's in or around hole with small stakes to hold in place. Mix up sacrete and pour in. Smooth with a trowel and let it set up. Bag should tell you how long.
Need more info. Are you making a walkway, a floor, steps? If a walkway you dig out the area where you want walkway at least 4" deep and try to keep bottom level. Usually made in sections with expansion joint(check with hardware) between. If a large job call company to deliver it. They can help you on how much to get. I have forgotten the formula to figure how many yards. Something about length X width and a certain depth is what I forgot. If it's just a simple above ground platform Lay out 2X4's where you want it. Remove just the top couple of inches of soil/grass. Place 2X4's in or around hole with small stakes to hold in place. Mix up sacrete and pour in. Smooth with a trowel and let it set up. Bag should tell you how long.
I think this tutorial can help you out!