laptop batteries

I bought a laptop today, for 50$.the only problem with it is the battery, and it only lasts for about an hour. So i was looking up batteries online, and i have a few questions :

What is Whr?
What is the difference in how many cells you have?

 

Whr is used to express the energy charged in kilowatt hours.

Battery cells are used to maximize safety and performance, so generally the more the better, however you shouldn't get too many because it can overheat your computer. Check out sites like:

www.batterysavings.com

for safe and affordable batteries.