Configuring, Buffalo WZR-HP-G450H to replace PN supplied TG528n

[#1]

Good morning. I have just had delivered this morning the above Buffalo product.
Having opened the box and read through the included airstation quick setup guide (guide shows a WZR-HP-G300NH2) I am assuming this is a generic quick start guide.
I am not sure how to go about setting up the buffalo to replace the TG528n. My PN welcome letter has all the details regarding accounts and passwords, but I am at a loss as where and how to input them for the Buffalo. 
Any help or guidance will be appreciated.
Ps: I have the fast fibre installed.

[#2]

Hi, I can't seem to find a downloadable manual for the WZR-HP-G300NH2.
Basically you need to set its WAN connection type to pppoe and input your PlusNet username & password.

[#3]

Just done a quick google search and the link below is the download for a pdf user manual for the WZR-HP-G450H.
Hope it helps

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC8QFjAA&url=http%3A%2F%2Ffoo...

[#4]

Thanks for that. Seems like it might be supplied with DD-WRT formware as standard. If so page 6 seems to cover the WAN setup. Set connection type to pppoe and then enter your PN details.