To upload a file to VirusTotal, you can visit the main analysis site, click the Browse button to select a file from your hard drive, and then click the Send file button. You can make this process even easier with the free VirusTotal Uploader utility. After installing it, you can simply right-click any file under 20MB and choose "VirusTotal" from the Send To Windows menu. The scan results will display in your browser as usual.
The latest version 2 of the VirusTotal Uploader utility adds a new program window with some useful extra features.