Okay: first you would need to add the database name to the connection string you use (plus any other specific data like user name and password). You wouldn't want to do this every time unless you were trying to access multiple databases: even then you might want to store these in a config file and access as required. I'm sure you can do the research required to figure this out.
Second, if you have a stored procedure like (very simplistic):
create procedure UpdateWhatever (@Param1 int, @Param2 nvarchar(50))
as
update table foo
set Col1 = @Param2
where Col2 = @param1
go
your program would pass the required parameters to the stored procedure using whatever method you deemed appropriate: again, do your research: I have no idea if you are using ADO or EF or whatever so hard to say how you should pass the data.
ps: Never say 'as soon as possible' or 'plz hlp': just pisses people off.