The CERT/CC recommends the following practices to home users:

Consult your system support personnel if you work from home

Use virus protection software

Use a firewall

Don’t open unknown email attachments

Don’t run programs of unknown origin

Disable hidden filename extensions

Keep all applications (including your operating system) patched

Turn off your computer or disconnect from the network when not in use

Disable Java, JavaScript, and ActiveX if possible

Disable scripting features in email programs

Make regular backups of critical data

Make a boot disk in case your computer is damaged or compromised

source:- http://www.cert.org/tech_tips/home_networks.html

The most common methods used by intruders to gain control of home computers are briefly described below. More detailed information is available by reviewing the URLs listed in the References section below.

Trojan horse programs

Back door and remote administration programs

Denial of service

Being an intermediary for another attack

Unprotected Windows shares

Mobile code (Java, JavaScript, and ActiveX)

Cross-site scripting

Email spoofing

Email-borne viruses

Hidden file extensions

Chat clients

Packet sniffing

source:- http://www.cert.org/tech_tips/home_networks.html

IP stands for "Internet Protocol". It can be thought of as the common language of computers on the Internet. There are a number of detailed descriptions of IP given elsewhere, so we won't cover it in detail in this document. However, it is important to know a few things about IP in order to understand how to secure your computer. Here we’ll cover IP addresses, static vs. dynamic addressing, NAT, and TCP and UDP Ports.
An overview of TCP/IP can be found in the TCP/IP Frequently Asked Questions (FAQ) at
http://www.faqs.org/faqs/internet/tcp-ip/tcp-ip-faq/part1/
and
http://www.faqs.org/faqs/internet/tcp-ip/tcp-ip-faq/part2/

source:- http://www.cert.org/tech_tips/home_networks.html

IP addresses are analogous to telephone numbers – when you want to call someone on the telephone, you must first know their telephone number. Similarly, when a computer on the Internet needs to send data to another computer, it must first know its IP address. IP addresses are typically shown as four numbers separated by decimal points, or “dots”. For example, 10.24.254.3 and 192.168.62.231 are IP addresses.
If you need to make a telephone call but you only know the person’s name, you can look them up in the telephone directory (or call directory services) to get their telephone number. On the Internet, that directory is called the Domain Name System, or DNS for short. If you know the name of a server, say www.cert.org, and you type this into your web browser, your computer will then go ask its DNS server what the numeric IP address is that is associated with that name.
Every computer on the Internet has an IP address associated with it that uniquely identifies it. However, that address may change over time, especially if the computer is
dialing into an Internet Service Provider (ISP)
connected behind a network firewall
connected to a broadband service using dynamic IP addressing.

source:- http://www.cert.org/tech_tips/home_networks.html

Computer security is the process of preventing and detecting unauthorized use of your computer. Prevention measures help you to stop unauthorized users (also known as "intruders") from accessing any part of your computer system. Detection helps you to determine whether or not someone attempted to break into your system, if they were successful, and what they may have done.

source:- http://www.cert.org/tech_tips/home_networks.html

We use computers for everything from banking and investing to shopping and communicating with others through email or chat programs. Although you may not consider your communications "top secret," you probably do not want strangers reading your email, using your computer to attack other systems, sending forged email from your computer, or examining personal information stored on your computer (such as financial statements).

source :- http://www.cert.org/tech_tips/home_networks.html

Here are some trick using your notepad to test your antivirus. Firstly, Open notepad and paste this

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

Then save it as eicar.com. Your Anti-virus will then either not let you save it of when you have saved it will remove it for you. Dont worry about it. Your pc not crash. European Institute for Computer Anti-virus Research (EICAR) have got people to program Anti-Virus to recognise this as a threat (even tough its completely harmless). You can read more about this trick here

source : http://www.bloggeraz.com/test-your-antivirus-working-or-not/

1. Stealing Passwords

2.Trojan Horses

3. Exploiting Defaults

4. Man-in-the-Middle Attacks

5.Wireless Attacks

6. Monitoring Vulnerability Research

for full article
source :- http://images.globalknowledge.com/wwwimages/whitepaperpdf/WP_Steward_Hackers.pdf