Can you help me fix the leak that is under the bathroom sink bowl?

We had to unclog a bathroom sink. When we replaced the pipes the fitting next to the bowl would not fit to prevent water from leaking. What do I need to do to fix the problem?

See the image below and tell us where is the leak at, Thanks.

John

we replaced the pipes the fitting next to the bowl would not fit to prevent water from leaking. What do I need to do to fix the problem?
The first thing you have to do is furnish me with more information. Do you have a metal or a plastic trap? Tell me exactly where the leak is, (see image).
Back to you, Tom