Purchase a laminated countertop from your local hardware store. The size of the countertop depends upon the area where you have to install it.
Take a measuring tape and note down the dimensions of the area where you desire to install the countertop. You will be very lucky if you get the laminated countertop of the same dimension as you measured and if not, you have to cut the countertop according to the required dimensions.
Cover up the surface of the countertop with blue painter’s tape. Re-measure the length and width of the area where the countertop is to be installed and then mark a straight line on the blue painter’s tape with a marker. Use a jig saw or any other appropriate cutting tool to cut the countertop along the lines you have drawn.
Sand the cut edges of the countertop to remove any splinters, making its edges smooth.
Place the countertop on the cabinets and against the wall to check out if it fits properly in the position. You should also ensure that installing the countertop does not hamper the opening of any drawers or doors nearby. Fitting of the countertop needs to be perfect and it all depends upon how accurately you have cut it according to the dimensions. If you find any areas which are not opening freely, you can use shims to lift up the countertop from there.
Use a carpenter’s level to determine whether the countertop is perfectly horizontal or not. If you find it slopping at any point, insert shims under the countertop to level it.
Now affix the countertop with ¾-inch screws from inside of the cabinets. Use a screwdriver to tighten up the screws.