Let me give you an example with Notepad:
Query the remote server to find the session ID you want to start a program in:
PsExec \\MyServer01 -u Administrator -p MyPassword query session
A list of session IDs will be displayed so look for the RDP or console session ID you want to start Notepad in. In my example, my RDP session is ID 2. Run the following command to start notepad remotely:
psexec \\MyServer01 -u Administrator -p MyPassword -d -i 2 C:\Windows\System32\notepad.exe
If you receive a message like "notepad.exe started on MyServer01 with process ID XXXX," check the remote session to verify notepad is open on the desktop.