Strange globe and folder with a question mark on it icons showing at start up screen, PLEASE HELP!

I got a PowerBook G4 tonight from my brother's friend. His friend said it's works fine, but he thinks it needs updated. It powered up fine at first. I looked around and found files that belonged to the previous owner (pictures etc) so I dragged them to the trash and deleted them from the trash. I couldn't get the wi-fi working. It recognized that it was there, but when I clicked on it and typed in the password, it wouldn't connect. So I took it out to our BTHomeHub and took the Ethernet cable out of the computer and plugged it into the PowerBook. I tried going onto Safari but nothing happened so I restarted it. When it loaded back up there's a globe icon that flashes and then a folder icon with a question mark on it, the first time it loaded past it. I held the power button down to turn it off and turned it back on again (hoping it would've disappeared) Now it won't load past that. I've looked around trying to find a solution, but nothing I've tried has worked. I even tried turning it on and off again, countless times. I'm really worried I've done something wrong and that it's broken! PLEASE HELP! (I'm not brilliant with computers, so simple instructions please!) 😢