GUI Web App Similar to Google Calendar: What should I use to make?

[es3]

Hey guys, I'm very familiar with programming etc. but GUI's are a pretty weak area of mine. I need to make a GUI app for my web page, that essentially displays a given week, and allows me to drag across it and have a given space in time be selected. The app would need to be able to graphically display what space was being selected and then return and process information back to the server (probably through ajax). Seeing as how I don't know much about GUI's I figured I would ask some direction before just diving in. I have some simple questions to make this easier I suppose:
1. What was Google Calendar made in?
2. What do you recommend a GUI novice like me makes this in?
3. Are there any sites you can recomend that I check out to learn more?
4. Misc/What else do you think I should know about this before starting?

[es3]

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