Hi, Joaquim,
Are you using VS2005 or VS2008?
Short answer...prior to VS2008, ADO.NET Select statements can't do the kind of JOIN statements that you're looking for. However, you can simulate a JOIN by using an ADO.NET Relation object and then using Parent/Child object syntax.
In VS2008, you can use LINQ to DataSets, which will allow you to use JOIN syntax.
If you need some actual code syntax, let me know....just want to find out which version of .NET you're using.
Kevin