Multiuser application on a local network

Question

Hi,
I have already worked with C# but only for simple applications. Now I have to build a multiuser application with a central database. I have already done a bit of reserach on this topic and I found that building a simple application and then deploying it on different pcs is a solution. But as my application will allow users to change data, how can i control if more than one users are editing the database at the same time? 
Thanks in advance.
Anila