You'll need to get a remote that is compatible with your Roku in order to set up a net connection. Once connected you can use the Roku app on a mobile device.
What model Roku is it, so we can advise on the remote you need?
- Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
- Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T
- TCL Roku TV 43S425/C107X, Ser X000001R60KV, wifi