First of all download git-tfs from there:
Right click on My Computer -> Properties -> Advanced system settings -> Environment variables -> System variables -> Path
Add ;C:\TfsMigration\GitTfs-0.25.1 to the end of Path variable.
Open Command Prompt as Administrator and exec following commands, don’t forget to change commands with your variables:
I use -c http.sslVerify=false because I have problems with my server certificate.
If your server configured properly, I recommend you to use previous command without -c http.sslVerify=false:
Full description about migrating from tfs to git you can found here: