This can be tricky.
If you are streaming saved content from your hard drive then your options are almost endless. However, if you want to forward live internet images (which are streaming to your PC) on to your TV then that can be awkward. I recently sought a solution to this and in the end I just bought a cheap laptop, about 4 years old, with a 'TV out' and ran it straight into my TV. As far as the laptop is concerned the TV is just a secondary monitor. This is by far and away the simplest and most reliable and most cost effective way of solving this problem. However, it is of course not nearly as neat as a simple software solution. (And also not nearly as pricey!) If you have a few hundred quid to spare then you could invest in a high end AV sender. But for me, all things considered, spending £80 on an old laptop was a much better value solution.