The "s" "i" and "t" extension

Hi every one,

well i refuse to beleive that there is not one single person who has an asterisk box, running realtime that hasnt figured out the 3 key extensions with regards to asterisk.

please please please can some one help, my realtime config works fine but i cant seem to build the dialplan i need with out using the s i and t etensions.

can any one help me