A missing shingle represents a vulnerability for your roof, thus it has to be fixed right away. You can leave this operation in the hands of roofing Southlake TX specialists, or you can do it yourself, as long as you have everything you need to work safely on the roof.
The first step is getting new shingles. You cannot purchase any shingle that looks similar with the ones you have on your roof, because it will most likely take a discordant note. You must take an existing shingle with you to the store, so you can compare and choose new shingles of the very same color.
Get a bundle of matching shingles, even if there is only one missing from your roof, because you will likely break a couple of them, especially if you are not a specialist.
The next step is preparing the accessories and tools you need: a ladder, some safety equipment (harness, non-slip shoes etc.), hammer, crowbar, prying tool, caulking gun and, of course, the replacement shingles.
Shingles are attached by roofing nails and tar. Remove the nails exposed from the damage and the tiles nearby if you must, to position the new shingle properly. See how many nails are used to fix each shingle and use the same number on the new shingle, but not before you aligned it with the other shingles.
When you are done, use tar to seal the nail penetrations, as well as areas where shingles lift up.