Most routers that support 802.11n will have that option enabled by default. Along with the router model as jpd asked about, what model is the laptop, and what OS are you using?
The router is a Netgear DGND 3300 v2. The speed is set to (upto 300Mbps @50GHz & 54Mbps @2.4 GHz) I think this it the bit needing changing.
I am Windows 7, the Laptop is HP dv7-3112sa
So your router supports 300Mbps at 5.0GHz, 802.11n, but your laptop only supports 802.11b/g natively.
Buy a USB wifi stick that supports 802.11n to make use of the available speed. Whwn you install that, make sure you set that as the default device and disable the existing wifi adapter.
Your computer is capable of receiving n speeds with that adaptor but you will need to check if it operates on the 5gHz band. I had this exact router and it is quite simple to make it operate on both bands. You will need to:
*login to the router by typing 192.168.0.1 into the address bar of your browser.
*input the username and password of the router (admin and password are the defaults)
*navigate to 'Wireless Settings' and on this page there will be a drop-down menu 'Mode'
*choose "Up to 300 Mbps at 5 GHz and 54 Mbps at 2.4 GHz" (this may already be your default)
This router broadcasts two separate signals for each band. Search for available networks and choose the 5GHz version if you can. The advantage of 5ghz is that it is laest congested. A principle of wi-fi is that everything slows down to the speed of the slowest device on a network. Given that the likelihood of an older device being one of the slowest and not having access to the 5gHz band, it makes sens to use this band if possible.
Ah, couldn't find the exact adapter spec, only site I found with specs for the laptop said b/g only.
Searching on that particular adapter specifies it's 2.4GHz only. Easy way to find out, specify different names for the 2.4 and 5GHZ networks, see if your laptop can find the 5GHz one.