Prefix all commands with

https://10.1.1.1/api/?key=API_KEY

&type=op&action=set&cmd=<show><user><ip-user-mapping><all></all></ip-user-mapping></user></show>

You can set User-ID information (the timeout value is minutes. Set it to 0 to never time out)

&type=user-id&vsys=vsys1&action=set&cmd=<uid-message><version>1.0</version><type>update</type><payload><login><entry%20name="LAB\user1"%20ip="10.0.0.1"%20timeout="480"/><entry%20name="user2"%20ip="10.0.0.2"%20timeout="0"/></login></payload></uid-message>