Keep in mind, if you attempt to display a .pdf on your web page (using embed or iframe tags), you are at the mercy of the viewer's settings whether it displays in browser, opens Acrobat or downloads as a file.
There is no way to force a pdf to display in-browser. If the viewer's settings don't allow it, it's not happening.
SnakeEyez has the right approach in my opinion. Link to the file and let the viewer's personal settings take it from there.
<a href="your_pdf_file.pdf">Click here</a>
PDFs are media files that require helper apps and plugins to open in browsers. Many people don't have them.
It's a nice courtesy to add a small thumbnail to give folks some idea of what the PDF contains. Also include the file size and a direct link to the file. As Jon said, end user settings vary quite a bit. You can't control what people do with PDFs.