Leyda, the most helpful thing you can do is post pictures of where the problems are occurring. If the people who understand your trailer can see the problem that you see, they can give you better answers.
Some questions that you will probably want to answer first...
Did it just start leaking?
Where is the leak/ water showing up?
Is there unwanted water inside the trailer beyond the leak?
Has it been raining?
Did you recently fill the fresh water tank?
Did you turn on an electric water pump?
Are you connected with a hose to a fresh water source?
Do you have a manual water pump?
And these may not even be the questions that get to your answer.