its quite easy to get sound output from those devices to your system, however i'm not sure it will be capable of surround sound on those devices.
your receiver only has analog stereo inputs, coax and optical. now while optical or coax are capable of surround input both the source devices and the receiver would need to support this (which is doubtful).
for stereo only sound you could use the tv's headphone jack or aux stereo out jacks (if it has any) and connect them up. for the roku (depending on model and connections it has) you could either use the analog outputs for l/r channels to the receiver or on hdmi only models you could use a hdmi audio extractor to get these l/r channels.
if you had a receiver capable of hdmi input you would be able to get 5.1 from the roku. depending on the model of roku you have, it might have 5.1 over optical capabilities however the destination device would also need to be capable of 5.1 input over optical as well. not sure what kind of audio outputs your tv has but many do not have 5.1 out, especially older tvs.
in short: stereo sound is easy, surround not so much.