...

To add a new assembly, click on Settings -> Library files. From the Assembly drop-down list, select Add assembly. Specify a species, if you can't find the species name in the list, choose Other, type in species name and assembly version (you may have multiple assembly versions for one species, like both e.g. hg19 and hg38 assembly versions for Homo Sapiens). You need to add the reference file which is a .fasta file containing sequence information. Once the reference file is added, you can build any aligner index to perform the alignment task. 

...