Moritz: Ok, this topic has not directly to do with Tcl but may very well be important for some Tcl developers who have to program a website in Tcl.
One good online ressource is the online book "Philip and Alex's Guide to Web Publishing" [L1 ] by Philip Greenspun. Btw, Mr. Greenspun uses Tcl and Oracle for website development and has created large websites in Tcl (I'll add links soon).