Create a plan for your loft and dorm space. Use tape measure to measure your mattress and room. Call your dorm adviser to find out about any special construction regulations such as clearance between bed and ceiling.
Choose a type of wood. Pinewood is a popular option. Take your measurements to a local lumber company or hardware store. Tell the clerk your plans and have posts and frame cut according to measurements. You will need four posts of the same measurement as well as a frame to hold the mattress. Allow for about 2 inches of space between the mattress and the frame. Purchase smaller pieces of lumber based on your measurements to construct a ladder.
Use heavy duty 3/8 inch carriage bolts to connect the frame to the legs or posts. Use screws, bolts and wood glue to connect the other pieces and reinforce the structure. Build the ladder to allow you to reach your bed.