Did you follow the steps in Clean Reinstall - Factory OEM Windows 7
which in Steps 9 and 10 is quite clear about how drivers are handled in Windows 7?
You were to download and unzip to CD or flash stick your network adapter from the Support Downloads webpage for your model PC or network adapter in case it was not in the Windows 7 installer, so that you can install it to get online to do all of the Important and Optional Windows Updates.
If you weren't clear about that step you should have asked ahead and not ignored it then ask back later as though you had not been clearly instructed on this from the start.
Tell us the make and Model PC, or if it's home built tell us the make and model of the network adapter you use to connect to internet. It may be listed in Device Manager, or you may have to trace it using Hardware Identification