Pinpoint is a Windows program for APRS.
To use with Signalink, see the Signalink How-to.
Once the radio, the Signalink, and the Soundmodem are configured, start PinPoint and change these settings:
You'll sometimes see a dash number after the callsign, this is called an SSID and they have different meaning depending on whether you're on APRS or Winlink. See the SSID How-To for more info.