datarelation in 3 tables

hello sir

i am using asp.net with c# and FarpointWebSpreadsheet control.

in that control i want output like this

-Description

      DescriptionLong

+Description

i have 3 tables===

tAsset----AssetCode PK. Descriptionlong

tSector---SectorCode PK. Description

tAssetSector----AssetSectorCode PK. AssetCode FK ,SectorCode FK

then how to setup datarelation between 3 tables.