Creating a Pinata Account and Uploading a Profile Pic
Upload your image: Upload —> File
Counter-intuitively, "Preserve file name" is often not what you want. Clicking it adds a parent folder (path) that contains your file. If you then try to link to the file, the IPFS now points to a folder instead of directly to the intended file.
The IPFS CID is how you identify your file on the network. Use this to link to your file. Apps will typically ask for a CID (sometimes just called a "hash"). You may also want to have a full URL to your file, which can look like this: https://ipfs.io/ipfs/<CID>