Use the UCSC Genome browser (https://genome.ucsc.edu/cgi-bin/hgGateway?hgsid=456934153_5jN1pHsO20ln0XuE8wrxgyjlA25w&clade=mammal&org=Mouse&db=0 ). If you have a not too big genomic interval (chromosome start_position end_position), you can take a look at what it contains.
If this interval is too wide, I am sure someone will provide you with a script to get all the genes near various regions.
Since your genome data is fasta (.fa), you'll need to use a tool like BLAST or blat to align the sequence to something known. The blat tool is here:
Just paste in your sequence, choose the right genome, and hit submit. You can then review the results in the UCSC genome browser.