If you tweaked the ASP page only, then:
1- Just copy-paste it to your website root folder (overwrite the old one). Like normal FileZilla copy/paste.
But if you tweaked both ASP page and the code behind, then you'll need to:
1- Re-build your project (Click Rebuild ... not Build)
2- By FileZilla (for instance) copy/paste your:
A- Modified ASP page.
B- The project ddl file.