Measure the width and length of the room. Figure the square footage by multiplying the width by the length. Plywood comes in sheets of 4 feet by 8 feet, which equals 32 square feet. Divide the square footage of the room by 32. This is the number of plywood sheets you will need to make your subfloor.
Place the ¾-inch-thick plywood in the room over the joists for a couple of days to let the wood settle and acclimate to the room's humidity.
Start installing the subfloor by placing the center of the plywood, smooth side up, over the joist in the center of the room. Line up the end of the plywood along the joist.
Stagger the plywood joints to give the plywood more strength; the linoleum will also look smoother if you do not line up the seams. Use a circular saw to cut the plywood as needed to fit the room. Work from the center line outward to the edge. Allow a 1/8-inch space between plywood sheets for expansion.
Use a variable-speed drill with a Phillips-head bit and 1 ¾-inch screws to attach the plywood to the joists. If there is a point at which the end of the plywood does not rest on a joist, create a blocker (a wood support) using a 2-by-4-inch piece of lumber. Place the blocker between the joists. The end of the plywood must be attached to a support or it will curl up.
Fill in the screw holes and any cracks in the plywood with wood filler. Let the wood filler dry. Sand with 120-grit sandpaper so the surface will be smooth under the linoleum.