ykgraduate

I want to ask TA,RA fellowship position to the schools (UC Berkeley, Carnegie Mellon) which admitted me. Because the foundation, which will give me scholarships, told me to get fellowships as much as possible. But, the admission letters indicated that they know I'm going to receive external funding from the foundation. Also, the admission to CMU is contingent upon receiving external funding from the foundation. Is it proper to ask about TA,RA? How can I get TA,RA positions, given that I have external funding?