Summarize:

Once you're certain that your brackets can hold your rod, remove it to attach your curtains. Most rods have stops at the end to prevent the curtains from falling off. Screw off one stop so you can slide on the curtains and secure them to the rod. Some curtains are attached to the rod by curtain rings while others are threaded directly through the rod. Consult the instruction manual your curtains came with if you're unsure. After you've attached the curtains, screw the stop back onto the end of your rod. Hang your curtain rod back onto the brackets to assess how your curtains look. If your measurements were correct and the brackets installed at a level angle, your curtains should enhance the look of your window. If your curtains are too heavy for the brackets, you may need heavy-duty brackets or a rod with added support. Cut your fabric slightly longer than your desired length, then pin your fabric up with needles. Use a sewing machine to hem the curtain in a straight, even line. Make your hem 1 inch (2.5 cm) longer than you expect you'll need to avoid shortening your curtains too much. If the curtain rods are uneven, your curtains may appear crooked or uneven. Measure your curtain rod with a level again and re-adjust the brackets as needed until the rods are straight.
Remove your rod to hang the curtains. Add the curtains onto the rod. Put the rod back into place. Hem your curtains if they remain too long.Take your curtains to a local seamstress or hem the fabric yourself. Check your curtains for crookedness.