To update your GitHub forked repository to that of the remote using TortoiseGit, follow the below listed steps:
- Add
upstreamrepository that has to be synced with your fork
TortoiseGit -> Settings -> Remote

- Fetch the
upstreamrepository
TortoiseGit -> Fetch

- Pull the
upstreamrepository
TortoiseGit -> Pull

-
Resolve any merge conflicts
-
Push to the
origin masterbranch
TortoiseGit -> Push

Hope this helps!