Ok, so you've got
this model apparently.
Because you say that Safari doesn't run I guess you're running a Pre-OS X operating system. You can verify this easily if the Apple icon on the upper left corner of the screen is not blue. This information is important for further support.
It's possible to install the first four flavors of OS X on this powerbook (OS X 10.0-10.3) but it won't install the newest version (10.4 aka "Tiger").
As was mentioned earlier, you can upgrade the RAM. But as you can see in the specs sheet, you must take away the 64MB RAM stick to do so because the Powerbook only has two slots.
On one hand, it's an old machine and I would think well about how much money you want to invest for RAM and Software, on the other hand if it is your first occasion to tinker with a Mac, there's hardly a reason to do so with MacOS 9.
But if you just want to connect it to the internet and if you're not interested in tinkering with OS X, MacOS 9 will do fine.
Search the forum for introductions to the Mac world, there were several topics about it in the recent months.