Source localization from .mat file

Hello Folk
is it possible to localize the source for each trial from ".mat file" into the Brainstorm tool? My data are as follows:
epoch: (64x500x750)
[epochs - EEG data (channel x sample x trial)
Total epoch length [-200 to 798] (i.e., 1000 ms). so total sample 500]

Could you please let me know detail process?

First you need to be comfortable with the Brainstorm environment. If you are not, follow the introduction tutorials (at least until #19) and the EEG/Epilepsy tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials
https://neuroimage.usc.edu/brainstorm/Tutorials/Epilepsy

Then, you should be able to load your file with the menu "Import MEG/EEG", selecting the file format "EEG: Matlab matrix". If there are other fields than "epoch" in your file, it would ask you which variable should be interpreted as recordings.

The best would be for you to load directly the original files instead of this custom file structure. If you have done your preprocessing with other Matlab tools, you can import in Brainstorm structures created with SPM, EEGLAB and FieldTrip.