A Web Interface is built into all Transmission flavours, enabling them to be controlled remotely.
Enabling the Web Interface
Refer to the Remote Management links in the User Documentation for your client to find out how to enable the Web Interface.
Accessing the Web Interface
Once enabled, open a web browser and direct it to http://ip_address_of_machine_running_transmission:9091/
If web browser and Transmission Daemon are on the machine you can use http://127.0.0.1:9091/
9091 is the default remote control port specified in Transmission configuration.