How to add frame XXX at specific locations on website

hello sir i need to learn to add frame using iframe in my elgg website at specefic location like at blog pages concerner with that topic or activity river or wire ....kindly guide me how to start and what files and where the coding is to be changed

will this lead to unstability in elgg ??? i will not be tampering with core engine but change has to be made such that the frame remains forever even if the site grows