Open the garage door fully and unplug the opener if needed
Remove any retaining screws or end caps holding the old bottom seal
Slide the old seal out of the track or pull it off the door
Measure the door width and buy a matching replacement seal
Cut the new seal to the correct length if necessary
Clean the bottom edge or track of the garage door
Apply a small amount of lubricant to help the new seal slide in
Insert the new seal into the track or push it onto the door edge
Center the seal so both ends are even
Reinstall any screws or end caps
Close the door and check for gaps along the bottom
Trim any excess seal if needed
Test the door opening and closing to ensure the seal stays in place