hi mate
you have several options avalible and these include :
1) a wireless usb adapter which plugs into any spare usb2.0 port* and then once you have installed the supplied drivers you can connect to any avalible wireless network ( * you can use usb1.0 however the speed is slower than usb2.0 and usb3.0 )
2) a wireless card .. this connects a "express cardslot" which is also known as a "pcmcia slot " and this is situated on the left ( or sometimes right ) of your laptop
3) wireless expansion card .. this is a small card that fits inside your laptop and this is the best option if you have a avalible wireless carslot ....
and the good news is most of these are relatively inexpensive and can be purchased for under £20 .... for a wireless usb adapter I recommend the "TP-Link TL-WN727N 150Mbps Wireless USB Adapter "( http://www.aria.co.uk/Products/Networking/Wireless/Adapter+-+USB/TP-Link+TL-WN727N+150Mbps+Wireless+USB+Adapter+?productId=39105 ) and for just over £4 this is a great deal ... simply plug this into any spare usb port and install the drivers ( in some cases windows will install the drivers for you ) ... then once this is complete right click the icon in the taskbar and select "view avalible wireless networks " then select your ssid ( wireless id ) and then press "connect" and then enter your wpa/wep wireless key
then theres the "Killer 1202 Qualcomm Atheros uPCI-e Wireless-N 2x2 MIMO 300Mbps + Bluetooth"( http://www.overclockers.co.uk/showproduct.php?prodid=NW-050-BF&groupid=46&catid=1597&subcat=2651 ) and this requires a internal slot inside your laptop .. you will see this if you open the cover on the back of your laptop,and if you have one this wireless card simply fits into the internal cardslot and then you install the supplied drivers ... this is a extremely fast wireless device and has a wireless connection speed of over 300mbps(megabytes per second ) ...and is a good choice for online gamers
finally theres the "D-Link AirPlus Wireless-G Notebook Adapter"( http://www.ebuyer.com/102352-d-link-airplus-wireless-g-notebook-adapter-dwl-g630 ) which inserts into the express cardslot as mentioned earlier .... this is ideal if you don't like anything sticking out of your laptop... and unlike the wireless usb adapter this wont fall out by accident ......
in summary theres many ways to connect wirelessly from your laptop and each have their good and bad points... however for simplicity the wireless usb adapter is the best ... and for people who don't like a adapter sticking out of the laptop you can also buy a "TP-Link TL-WN725N 150Mbps Wireless-N Nano USB Adapter "( http://www.aria.co.uk/SuperSpecials/Other+products/TP-Link+TL-WN725N+150Mbps+Wireless-N+Nano+USB+Adapter+?productId=52677 ) which is so small it will only be seen close up ....and for a 300mbps speed theres the "TP Link TL-WN823N 300Mbps Mini Wireless N USB Adapter"( http://www.aria.co.uk/Products/Networking/Wireless/Adapter+-+USB/TP+Link+TL-WN823N+300Mbps+Mini+Wireless+N+USB+Adapter+?productId=52566 ) ....
all the above wireless cards and adapters connect in the same way .... install the device/card and then select your ssid ( wireless id ) from the drop down list .. enter your wireless key and connect .. job done !
I hope this helps ... any questions let me know
good luck mate !