making WiFi work through out my place

WiFi has been a continuing challenge in my place. I have a tp-link extender but I don’t think I have it set up in my surf soho router. I would like directions on how to add it to the network. I would like to try that first before I buy a new extender. I also don’t know what software is needed to read the diagnostic report. The devices that I need to work via the extender uses 2.4 ghz.
Thank you,