You can upload CSV files from your computer to a BigQuery table of your choosing. If the BigQuery table does not exist, it will be created for you; the schema of the table will be inferred from the first CSV file you upload to the table.
You can also try directly typing comma-separated data into the text field and loading data this way.
After loading your data, you can view your data in the BigQuery dashboard in Google Cloud Console and clicking 'preview' on the table in your dataset.