DataSource Controls :: How To Lock Single Row For Update

i develop a c# windows application. My database is sql server 2008 exp. i want lock single row for user select it for update. for example;

userA - Connection a (connection id 52);

user select a single row (select * from t1 with(rowlock?, updlock?,or what) where id=1) and bind data to form fields (texbox, checkbox,combobox etc.). (there is no problem)

userB - Connection b (connection id 54);

userB can select all other rows from t1 (where id=2 or 3 or anything) but not id=1. when userB select * from t1 where id=1 system generate an exception with (you cannot select this row because it is updated. Updated users connection id is 52.)

when userA (connectionid52) close form or commit changes then userB can select id=1.

i am read few documents (transacions, rowlock,updlock, concurrency violation optimistic,pessimistic) but i couldn't understand.