Create a query with your 2 tables. You have a relationship between them right -- Asset_type_code.
You don't want Sum, you want Count I think.
Try something like this as a query
SElect AssetTypes.Asset_type_desc, Count(IT_Assets.asset_type_code)
from AssetTypes,IT_Assets
where IT_Assets.asset_type_code = AssetTypes.asset_type_code
group by AssetTypes.Asset_type_desc