You can upload files (<2GB each) into a project using the Environment tab in the side bar. These files will be saved permanently as part of your project. The most common use case for this feature is uploading CSVs as source data.
To upload files, navigate to the "File" icon on the left side of your project. Then drag your files into the "Drop files here" area or select your files from the "browse files" button as demonstrated below.
The "Copy file reference" option lets you copy the file name or Pandas
read_csv() code snippet.
You can download files from the file browser.