I have just purchased a notebook which is running windows 8 and I have created a homegroup on that notebook. I now want to join my PC which is running windows 7 to that homegroup but when I go into homegroup on the PC it doesn't ask me to join it wants to create a new homegroup. Does anyone have any solutions.

1. What is the complete error message that you are getting?
2. Which version of Windows 8 and Windows 7 are you using? To find out the version of Windows.
3. Which antivirus program is installed on the computer?
Some of the important notes while creating HomeGroup:
If a homegroup already exists on your network, you'll be asked to join it instead of creating a new one.
If your PC belongs to a domain, you can join a homegroup but you can't create one. You can get to libraries and devices on other homegroup PCs, but you can't share your own libraries and devices with the homegroup.
PCs running Windows RT or Windows 8 can't join a domain. You can only join a domain if your PC is running Windows 8 Pro or Windows 8 Enterprise.
In Windows 7 Starter and Windows 7 Home Basic, you can join a homegroup, but you can’t create one.
You can join a homegroup on a PC running Windows RT, but you can't create a homegroup or share content with the homegroup.
Typically, a homegroup is created automatically when you set up a computer with this version of Windows, but there are several things that could prevent you from creating one. To diagnose and fix common problems with creating a homegroup, first try running a Fix It wizard.
I would suggest you to perform the steps provided in the article.
Why can't I create a homegroup?
http://windows.microsoft.com/en-au/windows7/why-cant-i-create-a-homegroup
Also refer:
HomeGroup from start to finish
http://windows.microsoft.com/en-AU/windows/homegroup-help#homegroup-start-to-finish=windows-81&v1h=win81tab1&v2h=win7tab1