Where are you using Galaxy? Main server at http://usegalaxy.org?
If so, the Main Galaxy server at http://usegalaxy.org is undergoing upgrades for the pending new software release. This may temporarily involve short downtimes and slower response times, but will clear in the next few days.
If elsewhere, other issues could be a factor. Please share where by URL.
How to upload data (in most Galaxy instances): https://wiki.galaxyproject.org/Support#Loading_data
Thanks for using Galaxy!