My Acer laptop endeavour 5022 fan is too loud?

So,my aunt actually gave me this laptop.It is about 10 years old.Only it is like a new one!No problems on that!Web broswers are fast,programs run normally,hefty programs are a little bit late merely i guess that is normal,rightly?!
The problem is that the laptop's fan is opening too noisy.I know it is probably from dust that got stuck within the fan.But i dont know how to clean it up(if i am correct and the problem is dust).And also,i do not know what correctly to open in order to make the devotee.A little help anyone please?
PS:I remind that i have associate Acer Aspire 5022 Laptop(5022WLMI to be exact!)
Thanx in advance!