This is just a temporary fix, and shouldn't be treated as permanent. The next step up would be to have the chip removed, use a stencil to reapply solder on all the contacts, and then when the chip is perfectly in place it gets melted from the other side (through the chip) to melt it down before letting it cool.

Due to the difficultly involved in doing all this, I wouldn't take doing this lightly.

A complete alternative to this guide is to just identify the chip that needs reflowing, and using a heat gun to heat it up. If you have or can get something like kapton tape, do so. It can be used to shield everything around the chip you are heating up from being exposed to the same amount of heat and causing their own problem. Otherwise, use aluminium foil, along with some clips (I find the tiny ones you use for crafting work best, but be creative). Then finally heat away, making sure you have some understanding of what is too hot or not hot enough.

In regards to: What is meant by kilobyte, megabyte or gigabyte?

The answer to that question is the market value of how the conversion between them is measured, as you would expect if you purchased a hard drive. But in reality as they reach multiple terabytes, you loose a couple of gigabytes when you format it and look at it on your computer. Computers calculate on base 2 and to them, 1 MB is actually 1024 kilobytes, 1GB is 1024MB and 1 TB is 1024GB. By the time you add 2TB to your computer, you have lost 185.36GB. But in terms of RAM, probably not as noticeable.

In regards to Cleaning or Replacing Fans. Using a household vacuum cleaner to clean out the inside of a computer or other electronic could potentially be a ESD hazard, and hence isn't recommend.