There are two ways to share a folder from Dropbox website on Windows XP. You can hover the cursor over the folder's name and click 'Invite people to collaborate' to share a folder. You have another option to share a folder i.e invite people to folders from the 'Sharing' page. Create a new shared folder by clicking on 'New shared folder' button located at the top of the page and invite people to share a folder. Once recipient accepts your invitation, the shared folder will appear in the person's Dropbox.