Help with SQL Script please

Hi there,

What I`m trying to accomplish here is the following guys;

This would be the pseudo code that I`m trying to convert into proper SQL;

Declare @Parameter varchar(50)

now I`m trying to find out how to find whatever is in the @Parameter in the values of table column. something like this;

If @Parameter exists in (select column from table) then do something here else something else....

Thanks very much in advance for your help.