Preflop
With 5 players left to act behind you, JTo is a little marginal. I would normally open JTs from this position, but for offsuit hands the bottom of my opening range is usually QJo or maybe QTo, if the ante is very big. More important though I would never open limp, so if you want to play this hand, please raise it yourself. Having limped I would not fold to a small isolation raise like this though.
Flop
As played the flop is a mandatory check-call, when you flopped second pair.
Turn
You improved to two pair, but there are still many hands in his range, that beat you, so this is another check-call spot. He check back though, which you should be happy about.
River
This was literally the worst card in the deck, since any A or 9 now have a straight, and to add insult to injury a flush is also possible. It is definitely to thin to bet for value, since most of the hands, that might hero call, are better two pair or sets. And I also think, its fine to fold, when he bet. Its important to get past the basic level 1 thinking in poker, which is "I have two pair", and think about your hand in relation to the opponents range. And on this board there are a lot of hands, that beat JT. Its especially likely, he has an ace, since he raised preflop over your limp. If people have hands like 76s or 55, they will often limp behind, whereas AX is more often raised.
Conclusion
You played postflop very well, but limp-calling preflop is not a good strategy, and you are playing slightly to many hands.