Help needed with PR knowledge

Hi fellows,
Even though my thing has been PPC on google for the last few years, I just came across and bought from a friend a pr7 domain for cheap. Here goes my question. I am building a portal only 2 months old and im getting a lot of organic traffic already. What would the best way for me to use this domain to boost the PR for the other domains I'm planing to link to it, and how long would it take to get that . Also what would be the best way to link it do follow, reciprocal?
thank a lot

one backlink that is "do follow" transfers "100%" PR. two transfers each "50%". 3 transfers "33%".
The backlinks must be "do follow". Nofollow transfers 0% PR, they are just simple backlinks.

Reciprocal is not needed I think.

"do follow" gets transformed into **************** when I write so it's a reason on this post to write "do follow" (it's only a single word, not two words)

Thanks a los S-sheep very helpful

Don't do reciprocal link "exchanges" that doesn't work very well anymore. Just create a simple site on this PR7 domain with a few articles and link to the sites you want to boost in the footer without adding the nofollow tag, that will do the trick.

You can exchage your other site link with thsi better back link it do follow