Extending wireless range

I have a 3 com WL-540a router and a TP-Link TL-WA730RE router.

I have an existing router next to the phone line socket. The signal from the phone socket to upstairs gets quiet weak and to outside becomes random.

I got this 3Com router thinking I could use it as a range extender, by putting it on the other side of the house, where there is an ok signal, then get it to connect wirelessly to the existing wifi and then use the 3Com to extend the range of the current signal...and probibly strengthen the weak signal.
This did not work. It seems I need to run a cable from the existing internet conection to the 3Com router for it to act as a range extender.

So, I got this TP link router, thinking it could be the "wire" by acting as a access point between the 3Com and my internet connection. I have spent a few days trying and nothing seems to work.

I can't even turn my laptop wifi off and use a LAN cable to plug into the 3Com or TP link and get the router to connect to my existing internet source.

This must be a setting that should be on or off.... which I don;t know about.

Can someone give me a simplistic way of connecting the router(s) so they extend the range...ideally without me having to run a LAN cable from one side of the house to the other.

I have never used a range extender before, so this is all new to me.

Thanks
Ian