Your files are not uploaded anywhere technically speaking. The files are added into the IPFS local node.
When another node or a gateway is requesting the files, then they are requested and you send the data to the node requesting them.
If you are curious to know who has the files/data you can run:
ipfs dht findprovs $FILE_CID
$FILE_CID is the content identifier of your file/directory/data
If you are curious about where the actual files are added, in your local node, those are located in the datastore. By default the files are copied in the datastore when adding them, and you can find the data store in the default configuration directory (
~/.ipfs on macOS and GNU/Linux), but the content is in the "database" and no longer accessible as plain files.