I recommend that you start with our Gender Studies research guide here http://library.uhd.edu/genderstudies?hs=a. You will find our top databases for research in this subject area as well as some other helpful information. Try some of the following searches:
Depression AND LGBT youth
Depression AND race AND gender
LGBT youth AND race
I found some promising results in both the Gender Studies and PsycINFO databases. One article may be of particular interest to you - "Mental health disorders, psychological distress, and suicidality in a diverse sample of lesbian, gay, bisexual, and transgender youths", but there were a number of other relevant results. Use the boxes on the left hand side of the page to refine your search to full-text, peer reviewed, date of publication, etc.
I would also recommend that you take a look at some mental health statistics, which can be found in our Statistics research guide here http://library.uhd.edu/statisticsanddata?hs=a. Take a look at some of the resources under the Psychology topic.
Finally, we have a research guide designed specifically for your course here http://library.uhd.edu/psychresearch?hs=a. You will find many of the same databases found in the Gender Studies research guide, as well as other helpful information on the theory and process of research in psychology.