Joomla website: Teach & do Changing external javascripts + putting external content using iFrame

I have a joomla website. Have some existing external javascripts embedded. Need to remove some of them and put a new one. Also need to remove a few iframe pages (at least unpublish them) and put in a new one. I wish a freelancer shows me how to do these two while doing it so that I can in ongoing site management and optimization remove any scripts or iFrame content or change them later too. Collaboration on teamviewer/ any screen sharing device and clear and crisp communications ability necessary. U can conclude with a short help document displaying steps using screen shots. Bid after reading properly. The smallest bid slab is as side as 600-1500 so dont just bid at the top of the range. Work is small and so bid keeping that in mind.