Extending wireless range

[#1]

I live in a 3 storey house and struggle with the broadband signal around the house. I have recently purchased TP-Link WD8970 to extend the range.
I have purchased a home plug which I have plugged into the mains and the new router. The 2nd plug is into the mains on the 2nd floor. I have then plugged in my 'old' technicolor router through ethernet. I can see the plusnet router and it has a great signal but I cant conect to it worelessly.
I think I have created an access point but dont understand what I need to do to connect to the extention of the TP-link router. I have checked on the internet but I dont understand the 'technical' language used.
Can anyone help please?
Thanks
Sarah

[#2]

i hope you disabled all the router functions on the old technicolor otherwise you've got 2 routers on the network both fighting to deal with DHCP requests.

[#3]

Sarah,
There's a guide here explaining how to connect 2 Technicolor routers together to do what you want. Since all of the configuration changes are only on the 'salve' router it should be applicable for your situation. You will need to check the subnet and IP address of the WD8970 though to ensure you configure the Technicolor correctly.
Oops, it actually might help if I post the link http://npr.me.uk/together.html