Comey also stated Russia did in fact try to interfere with the election via hacking the DNC in favor of getting Trump elected. What they are looking into (as well) is if Trump's campaign colluded with that attempt.
Comey confirms: Russia wanted to hurt US democracy, hurt Hillary Clinton and help Donald Trump
Personally I doubt they colluded. Putin doesn't need help or permission of some Reality TV Chump. But this is all still a huge mess and Trump isn't helping with his Obama/Deep-State conspiracy theories and trying to get the public (mostly his uneducated southern/mid-western voters who mostly got him elected) to believe Russia didn't do anything and other proven lies.