Windows, itself, has a DLNA server that your TV can detect. For this to work the video format on the computer must be one the TV will recognize. This is more of a pain than it is worth because while TVs will do this the format and interface issues are too frustrating. IME, the dead easiest and most reliable way is to use PLEX media server on your computer and put a PLEX app on a ROKU, Apple TV or Chromecast. Whichever device fits your budget and other viewing needs. The miracast technology can do this too. I have no personal experience with miracast.
You will need really solid wifi if you plan on streaming high quality MKV files. One advantage of PLEX is transcoding so you can tell it to compress video when the bandwidth is not great enough. Plus you can then watch video on other computer, and your phone. It is free, but if you pay for PLEX you can stream over the internet. YMMV on this feature.
I love PLEX on my ROKU.