All of these players are unknown.
Pre Flop: ($0.07) Hero is BB with 9 
9 
2 folds, CO raises to $0.20, 2 folds, Hero calls $0.15
Flop: ($0.42) 7 4 5 (2 players)
Hero checks, CO bets $0.20, Hero raises to $0.60, CO calls $0.40
Turn: ($1.62) 7 
(2 players)
Hero bets $0.50, CO raises to $1, Hero calls $0.50
River: ($3.62) 3 
(2 players)
Hero checks, CO checks
PF: The CO raises to 4BB, it's more likely he has a stronger range here, top pairs and high cards. I call hoping to hit the set and stack him.
F: I don't want to bet and get raised by his possible overcards and flush draws so I opt to check/raise and assume that he will go all-in with hands which beat me so I can comfortably fold.
T: He calls and I opt to get thin value vs. the overcards and flush draws also blocking him from making a larger bet.
He min-raises, I'm unsure what to make of this so I just opt to call.
R: I decide I'll call a small bet if he bets the river but we get to see showdown for free.