Question : Problem: charging laptop battery

Hi, I know I am going to sound very dumb when I ask this but I am really new to laptops.  
My question is this:  
My laptop's (Toshiba Satellite) battery low indicator is flashing.  I am only able to use the laptop when I use the AC power cord.  It is a used computer and no matter how long I've left it on, the battery doesn't charge.  

Am I wrong to assume that this is how the battery charges?  Or do I need a battery charger to charge the battery??

Please help.

Thanks soo much.

cajoes

Answer : Problem: charging laptop battery

I have worked with a few satellit's before and have seen this battery problem before.  The solution to the problem was to:  With the computer turned off, take out the battery.  The computer must be plugged into the wall with the power cord.  Now turn on the computer with the battery out.  After the system has booted to the desktop, put the battery back in.  
The battery will charge while the laptop is plugged into the wall and it should only take a few hours, if that.