Read here to ensure system packages are installed
Download the agent from github releases
Create a directory for the agent and unzip. Use explorer or from cmd:
c:\ mkdir myagent && cd myagent
C:\myagent> Add-Type -AssemblyName System.IO.Compression.FileSystem ; [System.IO.Compression.ZipFile]::ExtractToDirectory("$HOME\Downloads\vsts-agent-win7-x64-2.102.0.zip", "$PWD")
c:\myagent\config.cmd
If you didn't run as a service above:
c:\myagent\run.cmd
That's It!