Random forest model gives same result for all test data, Next step?
Some of the possibilities include the following:

1) The training data has class imbalance.

Solution:


Train the model using CV = 5 or 10;
Do a log transformation to make the target distribution more normal in nature;
Check if you can add a weight variable that can fix the distribution.


2) Testing data is a small sub sample. Since it's Kaggle, I believe the testing data will be standard in nature, so the problem might be in the process that is generating the submission script.

As a beginner, you should use any benchmark script available in the forum to start with, which shouldn't have such issues.