SQL commands programatically in C#?

So I want a button to perform an insert command on a table. Any ideas? Basically, I want to add a field to a table using text from another form. Once the form pops up, I''ll return the string to my function that showed the second form. What is the command (not SQL command) to perform SQL command strings on my data adapter? Or do I need to perform the command on the data connection itself?