decoding radio digital modes without a radio, using WebSDR and fldigi

I’m interested in decoding radio digital modes without actually having a radio. The idea is that by using a web-based software defined radio (to tune in the signals) and the fldigi program (to decode the signals) that I should be able to “listen” to digital modes and start to explore the digital parts of the amateur and broadcast radio bands. I think I have all of the components, but I have yet to be able to get everything to work as expected. »