Diễn đàn hỗ trợ Firefox

How do I update Firefox? Or is this system out of date? I run OS X Yosemite 10.10.5

Hardware overview: Model Name: iMac

 Model Identifier:	iMac9,1
 Processor Name:	Intel Core 2 Duo
 Processor Speed:	2.66 GHz
 Number of Processors:	1
 Total Number of Cores:	2
 L2 Cache:	6 MB
 Memory:	4 GB
 Bus Speed:	1.07 GHz
 Boot ROM Version:	IM91.008D.B08
 SMC Version (system):	1.45f0
 Serial Number (system):	QP9210550TJ
 Hardware UUID:	138F1618-C38E-5368-BD77-394747EBEB39

I was injured and in the hospital a long period. my phone number was changed by my daughter from [telephone number] to [telephone number] my email changed because cable one closed all their accounts. It now is [email address]. Now I cannot log into my facebook account no matter what I do. It is the way I get in touch with my friends and relatives. What happened to my account? I was asked to log in with my name, Eileen Dueck and click on my picture to get in but that does not work. Nothing else works either. Please find my account and restore it.cannot l