Search for "free TV online" on a search engine like Google. Many different sites come up, some legitimate and some illegitimate. Browse these sites to see if any have high-quality episodes of your show.
Look for the show you want to watch on network websites. Most programming is available from the networks shortly after the original air date and remains online for a period of time afterward.
Find websites that offer streaming video feed from television channels. Most of these sites are free and provide access to television from around the world.
Check out sites like hulu.com, which offer many TV episodes for free. These sites contain both recent shows and older shows, derived from a variety of networks. The episodes are legitimately obtained and usually have ad content.
Find your shows at online video sites like YouTube. While most videos available on YouTube are too short for a full TV program, the site does offer some full television episodes.