Normally the report builder automatically creates links between two tables if you doubleclick on the table you would like to add. Only in some cases, you have to manually link them by drag and drop: Pull the column of one table onto it's matching counterpart of the other table. For information on which data is stored in which table, refer to the Database Dictionary. In this case, you would add 
tblADusers to your report and link 
tblAssets.Username to 
tblADusers.username and 
tblAssets.Userdomain to 
tblADusers.Userdomain. Afterwards, add 
tblADMembership and connect 
tblADusers.ADobjectID to 
tblADMembership.ChildADObjectID. Now add 
tblADgroups to your report and connect 
tblADMembership.ParentADObjectID to 
tblADgroups.ADobjectID. Now select tblADgroups.name to be displayed in your report and add a filter criterium to it. You might filter on the Last seen date of the asset as well in order to deploy only to computers which have recently been scanned.
Select Top 1000000 tblAssets.AssetID,
  tblAssets.AssetName,
  tsysAssetTypes.AssetTypeIcon10 As icon,
  tblADGroups.Name
From tblAssets
  Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
  Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
  Inner Join tblADusers On tblADusers.Username = tblAssets.Username And
    tblADusers.Userdomain = tblAssets.Userdomain
  Inner Join tblADMembership On tblADusers.ADObjectID =
    tblADMembership.ChildAdObjectID
  Inner Join tblADGroups On tblADMembership.ParentAdObjectID =
    tblADGroups.ADObjectID
Where tblADGroups.Name Like '%your group%' And tblAssets.Lastseen = GetDate() -
  3 And tblAssetCustom.State = 1