Paul from TLCC has release a short series of XPages tutorials at www.PaulDN.com. If you want to upderstand the basics of how simple xpages can rapidly be developed for web based apps based on Domino designer then this is for you. Paul explains the process and the relationships between the xpage components and rendering as well as discussing the differences from traditional Notes development. There are 5 tutorials (so far) culminating in Part 5 : Creating and Editing Domino Documents on an xpage. The tutorials relate to a free course from TLCC which you can find here.
I found some of Paul’s explanations very interesting as they don’t normally get mentioned in plain english and found out several things that I don’t think I would have come across myself. So even if you have done some playing around with xpages – this might be what you are looking for in getting to your first xpages app.