charging issue

So, found out the battery wasn't be charged the hard way after stopping after a long (1 hr.) ride and turned off the bike. Tried to start the bike and the battery didn't have enough amps to turn the engine over, and I got stranded a couple miles from home at 11p at night. Here's what I have...

Hey everyone, lokking for a little help. I just bought my first bike, it needs some things done. It doesn't seem to hold a charge very well, it has a new battery, what else could it be? Also, the previous owner said to flush it with sea foam... What is that/where can I get it/what do I do with...