Welcome to HT.
If you want to understand something, learn it.
and not only by reading, do some stuff your self.
for sql injections, learn SQL, its not hard and im not saying you should be a master with it, do some readings, install a mysql server or any other, test some queries … when queries run take anohter look at it and try to break it a part, if you can understand a query, and know how queries work it will be easy to exploit them.
for java script do the same, a bit of reading on basics, make your own simple scripts, read other scripts and try to understand them.
that goes for any programing language too.
the logfile injection is almost the same, but its bothe software/server related and code/script related.
if you learn html, javascript, php you can solve almost all levels here, add css to those and you can code websites ….
solve the levels and you can get the sites you make safer ….
im sure some people may offer to help with what you asked, but what i hope for is that no one does unless he made sure you did your part.
– WoW, long post, i must have nothing else to do :(
