Home Group Setup Troubles only with Win7

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: AMD Athlon(tm) 64 Processor 3200+, AMD64 Family 15 Model 95 Stepping 2
Processor Count: 1
RAM: 1919 Mb
Graphics Card: ATI Radeon X1200 Series (Microsoft Corporation - WDDM), 128 Mb
Hard Drives: C: Total - 381451 MB, Free - 253187 MB;
Motherboard: MICRO-STAR INTERANTIONAL CO.,LTD, MS-7327
Antivirus: avast! Antivirus, Updated and Enabled

Hi, I just added a new HP Win8.1 computer, and want to use this older Win7 as a secondary HOME GROUP computer. I've never set up a network before and I can't seem to figure out why I can't get it added to the group. I do not have a password on this Win7 unit and didn't want one. Is that the problem?

Please speak baby-language to me on this subject.

Thanks from Jack