The BAM dataset was uploaded successfully in a Galaxy server (local, cloud, public - was this http://usegalaxy.org)? Use FTP since the file is likley over 2G. Only load the .bam. A new .bam.bai is created upon upload.
Here are some examples for how-to: https://wiki.galaxyproject.org/Support#Loading_data
If there are problems, please explain what they are specifically. If tools are not recognizing it the input, double check the datatype assignment and potentially the database attribute (reference genome) and assign if missing. Click on the pencil icon per-dataset to do this, or these attributes can be assigned all at once during upload in that form.
Please share more details addressing some of the questions above, if this is not enough help. Jen, Galaxy team