Database Concurrent Access Issue

Dear All,

I have this .NET application that inserts lucky draw entries into SQL server. Each entry may have a range of values that the winning number will be drawn from. For example,

Entry 1: [1, 2]
Entry 2: [3, 8]
Entry 3: [9, 10]
Entry 4: [11, 11]
Entry 5: [12, 20]

The winning number will be picked from [1, 20]. Given this scenario, what is the best design that can handle the concurrency issue? If two entries are input at the same time, how to make sure it won't have the same starting value? Anyway to lock a table when one is accessing, disallowing other to run select query?

Thanks.