Mindiscover on "How save my rank while transferring the url"

I have an old wordpress.com site with the url http://www.hebrewtourguidetokyo.com

I bought this domain a new host to rebuild him on wp.org, and gave the old site my old domain which is hebrewtourguidejapan.com.

Now I need to 301 redirects all the pages from the other domain (japan) to the main domain (Tokyo).

btw, I changed the pages name so it won't be same address (/..)

Can someone please can explain that to me in a language I can understand?

Thanks