This post is for windows..and using firefox for yor web browsing....once you have downloaded firefox using this page:
https://www.mozilla.org/en-US/firefox/new/?utm_source=getfirefox-com&utm_medium=referral go to the directory that you downloaded it to eg:downloads...run the firfox exe file..... it will install ...follow its instructions.. you should get a few questions allong the way ..use common sense ....you should also be asked if you want to import anything from your old browser..click yes to import..this will transfer bookmarks and alike ...you may get asked if you want firefox to be your default browser..choose ...yes..finish the install ..then if using google chrome ..goto control panel..programs and features..in the list will appear ..google chrome..uninstall it then..reboot your computer... if using ..IE... just leave it installed because you will ruin your system with out an indepth knowledge of the operating system... here i have put together a list of poular addons i mostly use ..you have to go to this page
https://addons.mozilla.org/en-US/firefox/ bookmark this page as there are 1000`s to choose from you will have to install them one at a time it is a little teediuos that way... thubnail zoom ...thumbnail zoom plus ... adblock plus ...adblock plus pop-up addon ...updated ad blocker for firefox ...image zoom ...pdf viewer ...youtube flash player ...some i use but may not agree with you: ask for sanitize ...better privacy ... ghostery ...no script ...you may get asked to restart firefox after each adddon is installed ..click ..restart later... untill u have installed what you want then restart firefox.. next open firefox right click in the top of the page you should get a menu pop up..click menu bar... from here click tools..then addons in this page you will be able to edit the preferences to each addon.. this is a works in progress but should help you get started...