Finding my way through different databases

Good afternoon,

I am new to DepMap and am not really sure how to navigate through all the data. For my internship, I am interested in finding a database with information of the genes that are mutated in/have an effect on a tumour in as many different patients as possible.

I found a lot of different databases that could be downloaded, but I’m not sure which would be the most useful and how I would then know what is in the database (or in other words, which information I can use to find out which combinations of genes often have an increased expression in tumours).

Do you have any tips on where to start?
Thank you!

This seems like a general question that goes beyond just the DepMap portal. Are you familiar with https://www.biostars.org/ ? They’re a great resource for asking general bioinformatic questions.