Tab-top curtain panels are the type with straps of fabric across the top. The straps, or tabs, form loops that hold the curtain rod, rather than the more common pocket of fabric across the entire top of each panel. Tab-top panels are easier to hang than the pocket style because there is less fabric to push the rod through; the biggest concern is ensuring the curtain rod is narrow enough to fit through the tabs or straps.
Pull the curtain rod down from the rod holders, climbing a step stool or stepladder if the rod is too high to reach comfortably. Wipe down the rod with a dust rag if it has been in place over the window for a while; cleaning it while it's within reach is convenient and easier to manage than while it's above a window.
Hold the end of one curtain panel near the end of the curtain rod to determine whether the tab or strap fits over the finial, if any. If the finial is too large, remove it by turning it counterclockwise or pulling it straight out. Some finials have a set screw; loosen a set screw using a Phillips screwdriver.
Position the curtain panel so the front of the panel faces you. Push the rod through the first tab, followed by the second and third, until the entire panel is on the curtain rod. The first tab can be either the rightmost or leftmost tab depending on whether you're working from the right or left side of the curtain rod. "First" means the tab that should go onto the rod first in order for the panel to be properly fit on the curtain rod, front side facing the room. Repeat this for all remaining curtain panels. Replace the finial if it was previously removed.
Hold the curtain rod toward the center, lifting one end to fit it back onto its respective rod holder. Climb a step stool or ladder, if necessary. Position the other end of the rod on the remaining rod holder. Slide the curtain panels so they're evenly aligned over the window, such as one panel on either side, or two on either side.