how do i attach folder with 20 scanned documents that are on my desk to via google chrome

If they are PDF files, following tip could solve your question.

http://support.apple.com/kb/HT4075

if not, compress the whole folder into one file with right click on the folder and select "Compress "Folder"".

Then attach it and semd via email.

You can't drag a folder into webmail, but you can either drag the individual files, or create a zip archive by right-clicking on the folder and choosing "Create Archive". Then drag the resulting file into webmail, if your email service allows a file of that size. If not, you'll have to use a file-sending service such as WeTransfer.

Matt