Connection Problems

[#1]

Hello all. I am a 74 year old teenager and this is my first time on the forum. My disabled grandson has been given a 3 year old desktop with XP and a Netgear USB adapter and software which he wants to keep at our house so he can use it when he comes.
The previous owner has taken the broadband off the machine so I have tried to put plusnet on and I get so far then I cannot connect although the Icon at the bottom  is showing a little laptop in green and when I click on it it says I am connected. What am I doing wrong.
Ken
Dick:green Colour tags fixed.

[#2]

What happens when you try to open up a browser like Internet Explorer?

[#3]

When I try to open any web page like Internet Explorer a page come up say unable to open this webpage' 

[#4]

Hi, just tried calling you but you were busy. Let me know when it's convenient to call back and I'll try and help you get it set up.

[#5]

Thaks for your call and sorry to have missed you but I was helping a chap with his car and I could not leave the drivers seat. Anyway I will be in at about 3.00pm so if you can ring about 5 past 3
by the way I reformated the hard disk and it is a bit bedtter inso far as it comes on OK but after a little while it goes off and the netgear icon goes red and the Plusnet  icon has a little yellow thing moving about and again after a little while it cleare and everything is OK untill the next time.