It would help to know what browser (and version) you are using...
Recent versions of Internet Explorer have built-in parental control which can block *most* (but not all) "prone"; have you tried searching for "parental control" in your browsers' help.
Remember that software can be easy to by-pass and people are savvy to these procedures. If you are protecting youngins from accidentally happening upon these sites this might just be your huckleberrry.
hi.....my name is venkat......i'll give u a small idea.....u just go to goole search engine and type software to block pron sites then u'll get some softwares over there .........u just download it and run it